I don't remember the specifics, I remember that after designing the UI files on QtDesigner you had to compile some files that python consumes, some sort of bindings to the interface you created.

You never had to do that. You can load Qt Designer XML files at runtime with neglible performance impact.

I still like to use pyuic so that the IDE will pick up the generated file and suggest widget names while you’re editing the subclass. Otherwise you’re a bit blind.

It’s trivial to add pyuic as an external tool in most iDEs anyway.

Good point, though I personally don't work through self.ui but rather prefer loading into the class itself. Then I just put type annotations of the widgets in the class.