as he said, his computer isn't that important. It only matters that other people that submit, who are going to rate the games, can play it.
itch.io lets you upload any files i think, so if you really wanted to support 32bit, nothing stops you from also exporting and uploading that.
In general, in game jams, if you can also do a web export, that tends to mean more people play, just because it's easier and less effort to start the game.
MVM generally having slightly """larger""" games tends to have a lot of games that can only be downloaded, no web. So you shouldnt be at a big disadvantage if you don't have it playable in the browser, i think.
If you do choose to try to export it for the browser - i know Godot says that you should probably use GLES2 instead of GLES3 for compatibility reasons.
Firefox also refuses to play the exported .html directly - but if you upload it to itch it works, and maybe i remember incorrectly but once you set up the html export settings i think a button appears in the top right of Godot to quickly export and run the game? Not sure...
Last thing, AGAIN i don't remember the details because it's been a while since i used Godot but there are some audio formats that have a few issues in the browser, you should search that and avoid them if possible. if you are exporting for web of course.
Good luck with the jam!