Have you ever tried to deploy a native looking Python3 qt app on both Mac and Windows? I am not aware of anyone who lived to tell the tale. If you can do without a native look (menus, dock icons, app packaging), i.e. you just want to have some academic lab tool, then qt is good enough, IMHO. But no comparison with native UI development on Win or Mac.

no, linux only. i'll admit that i wasn't taking native look into account, but then again, no default gui toolkit would be likely to have a native l&f anyway - you'd want to use the platform-native bindings for each platform separately, if that was a strong concern.

Nothing per se. However the situation with two competing python bindings and no official out of the box support or blessing of either makes it non-obvious as to what the 'correct' way to write and ship GUI apps in python is.

If I just want to wrap a simple GUI around some functions then going down the qt route is currently far to 'heavy'.