Ok...I created an account just to share this. So bare with me.
- Enable AUR
- Download multimc from the AUR
- Edit the build options (You want to change "arch=('i686' 'x86_64')" to "arch=('any')"
- Build it ( This takes a while)
- While that is building you are going to want to download LWJGL 3.2.3 (1.16 uses LWJGL 3.2.2 and will happily run on LWJGL 3.2.3). Make sure you get the arm libraries when you download it.
- Once Multimc is done downloading. Create a 1.16 instance.
- once that's done edit the instance. Go to version, click on org.lwjgl3. click on modify, then edit. This should open up a text file. Select all the text, hit delete and save.
- Extract the zip that all your LWJGL libraries came in to a directory you know.
- Click add to minecraft.jar in multimc (same page you selected org.lwjgl3 from earlier)
- browse to the file you extracted the LWJGL libraries from earlier to and add them all as jar mods.
- assuming you've done everything correctly. You should be able to launch Minecraft now
I locked the framerate to 30 since my Pi lacks proper heatsinks (they're in the mail) and the poor thing had issues with overheating.