Let me flood you with a million links that just might help.
First thing is to determine what serial number you want to get for a modable switch:
https://gbatemp.net/threads/switch-informations-by-serial-number.481215/
Once you get your switch, you need to find a way to boot into RCM mode:
https://gbatemp.net/threads/the-ultimate-list-of-mods-to-enter-rcm.502145/
RCM mode is basically a recovery type mode that we use to push the custom firmware (CFW) files. Typically done by shorting a pin in the right joycon rail to make the switch tablet think you're holding it's non-existant home button while you also hold volume up then press power. Be careful what method you use as you COULD cause damage to your switch ie. jamming a screwdriver into the side. There is also an option you can enable through hekate (check the atmosphere tutorial below) that will make the switch automatically boot into RCM mode
Next, you need to choose a custom firmware that you want to run, there are a few differences but in the end they all help you achieve homebrew. Right now it seems like we have 3 options so I'll link you to guides on each
Atmosphere:
https://gbatemp.net/threads/guide-universal-cfw-instalation-guide.517122/
ReiNX:
http://reinx.guide/
RajNX:
https://gbatemp.net/threads/rajnx-c...free-starter-pack-for-nintendo-switch.513785/
There's also SX OS but that stuff is not free but hey the easy to use dongle is nice if you're willing to drop the money so here's their official site:
https://sx.xecuter.com/#prod-sxpro
Another semi-cfw-related link I'll post is to painless linux which is just linux running on your switch:
https://github.com/natinusala/painless-linux
The above guides cover everything in pretty great detail. Before starting always make sure you back up your NAND and boot files so you have a "clean" backup in case something goes wrong (which is pretty unlikely) And definitely don't jump right in before you read everything over and get an understanding of what exactly you'll be doing. Which, jist of it all is, you force your console into a a recovery type mode (RCM) plug it into your computer, install drivers for your PC to read your switch, then push the payload file to patch a few things and get the CFW up and running. Once in custom firmware you'll be able to open the picture album and launch the homebrew menu so you can run those sweet sweet emulators (or whatever homebrew app you're after) It's really quite simple, maybe a little overwhelming, but not hard at all.
I recommend checking out the Homebrew development section of the forum to find some homebrew apps to run and play with:
https://gbatemp.net/forums/switch-emulation-homebrew-software-projects.292/
I hope I was at least somewhat helpful in pointing you to some useful information.
