It's possible but you still need to know what all your assets are before hand so itch.io can serve them. Using the godot/javascript bridge you can use the browser fetch api to download more assets (like .pck files) as the game is running. It's a bit overkill though, 99% of gamejams in godot do not need this. Just try keeping your assets under 200mb and you'll be able to export to web easily.
Ours is 224mb and we have to split it up but it's not too bad
Yoooo godot gang! I just noticed there was a discussion board here. We are also doing 6 Mesh3d planes so we can assign an image (or video!) to each surface. Godot has been working smoothly for us. The only roadblock so far has been splitting up the index.pck file for web exports into smaller chunks and then loading them (only a problem if it's > 200mb). It is possible, but feels like a hack
