and seemingly struggle to upload different builds for the same OS,
With the current system, you can upload different builds for different reasons. This includes supporting different CPU architectures, and support 32 bit and 64 bit systems. It is then up to the user to make the right choice and download the right version of the app, but if unsure, they can download multiple versions and try each one.
What you are suggesting would only work for the Itch app, so that it can automatically play a compatible version, although I’m not sure if the Itch app can do that already or not.