I noticed there's no one talking about this, so I'll talk about it! You can actually install Luma3DS directly to your FIRM0, replacing B9S with Luma3DS! This is not recommended for newbies and neither I nor the Luma3DS team are responsible for any possible damages that may happen.

Requirements

A 3DS running B9S or Fastboot3DS
Luma3DS
GodMode9
Your favorite beverage of choice.

Installation Process

Assuming you've already followed The Guide and you are already running the latest version of Luma3DS, I will just start what you need to do to get Luma3DS installed as your FIRM0. Please excuse the mess on my SD/CTRNAND, these screenshots were taken on Goat
1: Boot into GodMode9 either using Luma3DS or Fastboot3DS
2: Navigate to where you have your "boot.firm" store.

[0:] SDCARD (name of SD): boot.firm

[1:] SYSNAND CTRNAND: boot.firm

3: Press A on the "boot.firm"
4: Press A on the "FIRM image options..."

5: Navigate down to "Install FIRM" and press A

6: Press A on "Install to FIRM0" and follow the key prompt it should say "Install success (<A> to continue)

7: Reboot system, you now have Luma3DS installed as your FIRM0
8: Enjoy your beverage

F.A.Q.

Q: Why would I want to do this?
A: It cuts out a middleman exploit like B9S and boots directly into Luma3DS. If that's something that sounds beneficial to you, then give it a try.
Q: How can I update this setup?
A: Download the latest version of Luma3DS and follow through the Guide again. There's really not easy method setup for this as of writing this guide.
Q: What if another update like 11.8 happens? Can I fix that?
A: If another update like 11.8 happens, you can fix it by just following the same steps above. Luma3DS boots long before the NAND is even mounted, so you can still boot into your B9S payloads through Luma3DS.
Q: Can I still dump my boot9/boot11?
A: No, you will either need to reinstall B9S/Fastboot3DS to dump them or dump them before following this guide.
Q: How can I revert back B9S/Fastboot3DS?
A: Reinstalling B9S
Reinstalling Fastboot3DS. It's worth noting that the same process used to install Luma3DS can be used to reinstall Fastboot3DS.

 

[The Catboy]

What's an mcu brick? Is there any other way to fix it?
Also kind of unrelated side note, but if you were to force restore a nand backup from another system that would still be fixable right? Just to be sure.

An MCU brick is brick caused by extreme circumstances. The most common cause was during the A9LH when you had to downgrade your new3DS to 2.1 and the system would brick if you put into sleep mode. This was caused because 2.1 wasn't made for the new3DS hardware and couldn't wake all of the chips when trying to wake the system out of sleep mode. Nowadays MCU bricks don't happen under normal circumstances because the average user isn't messing with their MCU nor do they have to downgrade their system to hack it anymore. There was no known way to fix it, not even Nintendo can fix MCU bricks. Of course this isn't a worry anymore because we've moved past those risks.
Being that NTRBoot is a bootrom exploit, it works long before the NAND is mounted. So you can still recover your system after doing something restoring another system's NAND onto your system.

 

[SirNapkin1334]

As I said in the OP

I really don't have nor know who's the target demagogic for this guide, maybe tinkers like me? I thought it was pretty cool when I first installed Luma3DS to my FIRM0 and played around with it. Whenever I test payloads/CFWs, I actually do test them all on B9S, Fastboot3DS, GM9, and Luma3DS to make sure they work on every method of FIRM0 booting.

It's literally the same process as installing Luma3DS to the FIRM0. I personally ran SaltMode9 (GM9 bootloader, but it used the start button to disable autoboot and also didn't have a bootsplash,) before switching to FB3DS. I could make a brief write up about it since there are some differences in how the bootloader looks and operates verse how GM9 normally functions.

Haha, same exactly - I used SM9 until I switched to fb3DS.

 

[ry755]

Each kernel partition - up to 8 !

Do you mean there could be FIRM0 up through FIRM8? Or is the kernel stored somewhere else?

 

[SirNapkin1334]

What's an mcu brick? Is there any other way to fix it?
Also kind of unrelated side note, but if you were to force restore a nand backup from another system that would still be fixable right? Just to be sure.

Essentially, it’s when your MCU chip gets fucked up in some way. One common way was, as aforementioned, closing the lid on a n3ds on 2.1. Another one involved spamming LED-based commands on a system <9.0. I think if you fuck with LEDs enough, it can Brock, but that might be fixed nowadays. Anyway, it could potentially be fixed by replacing the MCU chip, but that’s...hard

 

[ry755]

Anyway, it could potentially be fixed by replacing the MCU chip, but that’s...hard

At that point you might as well just buy a new 3DS, or at least replace the mobo

 

[OrGoN3]

At that point you might as well just buy a new 3DS, or at least replace the mobo

Or spend $20 on a compatible flashcard, instead of $100+ on a new system.

 

[SirNapkin1334]

Or spend $20 on a compatible flashcard, instead of $100+ on a new system.

Please read the above posts. It was stated that MCU bricks cannot be fixed by flashcarts, hurr durr

 

[OrGoN3]

Please read the above posts. It was stated that MCU bricks cannot be fixed by flashcarts, hurr durr

For some reason, I always think MCU bricks are fixable by NTRBoot. Obviously I'm mistaken. And yes, I would just buy a new 3DS at that point as well.

Also, I always figured nobody installed Luma3DS as firm0 was due to the many updates and the pain it is to update the firm0 every time. Now that Luma3DS is most likely nearing its final versions (as the 3DS system software is) this wouldn't be a terrible move. I just feel that since you lose NAND backup/restoring, it's not worth it.

 

[The Catboy]

For some reason, I always think MCU bricks are fixable by NTRBoot. Obviously I'm mistaken. And yes, I would just buy a new 3DS at that point as well.

Also, I always figured nobody installed Luma3DS as firm0 was due to the many updates and the pain it is to update the firm0 every time. Now that Luma3DS is most likely nearing its final versions (as the 3DS system software is) this wouldn't be a terrible move. I just feel that since you lose NAND backup/restoring, it's not worth it.

You can still run payloads like GM9, you really only lose the ability to dump the bootroms

 

[Ryccardo]

Do you mean there could be FIRM0 up through FIRM8? Or is the kernel stored somewhere else?

Yes (almost: counting 8 starting from 0 gets you to FIRM7), if you are sufficiently bored to repartition your internal storage

The official 3DS-mode (and recovery, DSi, GBA) kernels are found on ctrnand, and that's why "modern" cfw can boot them from there without needing a firmware.bin or whatever, even though the kernel partitions have been replaced by, typically, some forwarder to the cfw

 

[Sayora]

How would you make firm7? I'd imagine it just tries the first one that isn't corrupted. But how do they get corrupted?

 

[Deleted User]

I like having multiple boot options so i wouldn't do this unless I only used luma.

 

[Sayora]

I would probably at least flash godmode9 to firm1 as I believe (please someone correct me if I'm wrong) that firm1 will only load if firm0 can not load. Godmode9 is the only firm that can flash to firm0 so if firm0 is corrupted and firm1 boots you'll be able to tell and be able to easily reflash firm0.