As you know you can normally run android and Linux on unpatched switches but patched Switch is not as great as the unpatched one so don't expect much.

1- Don't blame this guide if you damage/brick your switch, rather blame yourself because you couldn't even follow a simple guide.
2- This guide hasn't been tested on Marikos, so it is NOT guaranteed to work.

Spoiler: Android 8.1

NOTE1: This guide will cover how you can root your android. If you don't want to root it then skip the steps which are Italic.

NOTE2: For the latest updates: XDA

NOTE3: Couldn't make the SafetyNet work on Magisk.

PART 1: GETTING THE FILES:

Antutu Score: 131,518 (This is just a Netflix, Youtube, a web browsing and TV Casting machine right now!)

REQUIREMENTS: Micro Sd Card Adapter (In case your pc doesn't have it), A second Micro sd card which is at least 16 GB.


Step 1: Close your Switch and then open it's micro sd card on your pc, after that copy the following files into a folder: boot.dat, hbmenu.nro, license.dat, license-request.dat, sxos (folder)
Step 2: eject your micro sd card from pc and put your 2nd micro sd card into pc.
Step 3: Download your android image according to your micro sd card's storage (https://download.switchroot.org/android/), download shiledifier.zip, after that download fix-joycon.zip from the extras folder in the same site.
Step 4: Download ARM64, Android 8.1, nano(https://opengapps.org).
Step 5: Download the latest Magisk archive (https://github.com/topjohnwu/Magisk/releases).
Step 6: Download the latest version of Hekate(https://github.com/CTCaer/hekate/releases/tag/v5.3.2).
Step 7: Download balenaetcher(https://www.balena.io/etcher/) and then set it up.
Step 8: Run balenaetcher, choose your image file, then your 2nd micro sd and lastly click flash. Be patient since it can take some time.
Step 9: Copy the files you got from your initial micro sd card to the 2nd micro sd card's root.
Step 10: Open Hekate archive and extract everything to the root of micro sd(If it asks, replace the existing files).
Step 11: Move all of the archives(except Hekate) you downloaded to the root of the 2nd micro sd card (without extracting them).

PART 2: SETTING UP ANDROID:

Step 1: Put your 2nd micro sd into your switch.
Step 2: Press down power and "+" buttons at the same time until you see SX OS Boot Menu.
Step 3: Press options then press payloads. Choose Hekate payload and then click launch.
Step 4: Click "More Configs" and then start holding "+" button, click onto the Android logo.
Step 5: Hold "+" button until you see the TWRP menu. Swipe up.
Step 6: Select Mount from the menu. Then enable the System partition. After that, click Select Storage.
Step 7: Choose micro sd card from the pop-up menu and then click OK.
Step 8: Press the android home button and then choose Install from the menu.
Step 9: Select open_gapps archive then swipe right. After that press Wipe Chache and swipe up.
Step 10: Go back and then press magisk archive, after that swipe right, wipe cache, and swipe up.
Step 11: Go back and then press fix_joycon archive, after that swipe right, wipe cache, and swipe up.
Step 12: Go back and then press shieldifier archive, after that swipe right. (Nvidia Games didn't work on me.)
Step 13: Press Reboot System, swipe right, then hold the power button for 15 seconds.

PART 3: BASIC ANDROID SETUP:

Step 1: Get into the Hekate as mentioned in Part 2, Step 2-3. (There might be blue light coming from the back of your switch during boot up, it's nothing to worry about, be patient and it will boot eventually.)
Step 2: Click "More Configs" and press Android. (DON'T Hold "+")
Step 3: Wait for at least 30 seconds if nothing happens press the power button for 15 seconds and then repeat Part 3, Step 1-3 until you see the menu.
Step 4: Follow instructions from the screen. (DON'T CONNECT TO WIFI UNTIL SETUP IS COMPLETE!)
Step 5: ..... YOU SUCCESSFULLY INSTALLED ANDROID TO YOUR PATCHED SWITCH!
Step 6: Download Magisk Manager APK (https://github.com/topjohnwu/Magisk/releases) and run it.
NOTE4: If you want to boot into normal switch, you should just swap micro sd cards.
NOTE5: Battery still drains fast, approx. 2-3 hours.

CREDITS:
-Sthetix's Unpatched Switch Running Android Video (I adapted this guide from he's unpatched switch guide.)
-Android LineageOS Creator: switchroot

Spoiler: Android 10

REQUIREMENTS: Micro Sd Card Adapter (In case your pc doesn't have it), A second Micro sd card which is at least 16 GB.

Step 1: Format the SD Card to FAT32. (You can use GUIFormat for Windows and GParted or your distros partition manager for Linux.)
Step 2: Download SX Gear from the SX Portal and download the latest Hekate. Extract Hekate archive and copy these to Micro SD Card.
Step 3: Rename hekate bin to payload.bin
Step 4: Follow this guide.

CREDITS:
- Switchroot Team - XDA ROM Page

 

[Sickem96]

It's not about the SD too most probably.
Were you able to boot into TWRP by holding the + or you weren't able to boot at all?

I can't boot anything: no twrp no android. I waited few minutes each boot too.

 

[GCS]

I can't boot anything: no twrp no android. I waited few minutes each boot too.

(Just to make sure) were you pressing the volume up button during boot?

 

[Sickem96]

Yes, of course i were. I tried to start pressing before launch Android but also then i clicked on Android icon.

 

[RONINN]

Hello, is it possible to run LineageOs on Switch V2 / SX Core. Firmware Picture 13. Please answer and give me a hint.