You have to post your game on Itch.io in order to participate in the rating and review part of the jam.
If you want to post your game anywhere else (whether that's the Meta Store, some other store, your own website, whatever), you can, but that's up to you
You can test it on whichever AR or VR devices you have. Sure, you can post it anywhere you want - the jam is only concerned with what's posted on Itch.io
