Heya, I don't know if this got resolved but I was able to upload my 4gb game using the butler extension for the Itch App.
https://itch.io/docs/butler/
The documentation can be a little tricky to understand but once you getting it running it's pretty simple to upload larger file sizes
I don't know the limit for file sizes when uploaded this way but I did read that someone uploaded over 30GB this way.