I'd like to see it do that on macOS ...
You're seriously suggesting that the common use of Qt on Linux systems is direct rendering without the windowing system?
You're seriously suggesting that the common use of Qt on Linux systems is direct rendering without the windowing system?
Arguably it's use in embedded contexts is much larger than desktop. It's quite popular for in-car computers, defense systems, etc.
For desktop linux, yes, it uses the windowing system.