I've finally just submitted the RFC series for USB3 support on Apple Silicon machines. RFC because the entire Type-C machinery spans multiple subsystems and has quite a few quirks which makes the entire thing rather annoying to deal with and I'm not 100% convinced about the current approach.
This also includes some initial work for DisplayPort-altmode and USB4/Thunderbolt but both will require much more work after this is upstream, so don't get your hopes up just yet.
https://lore.kernel.org/asahi/20250821-atcphy-6-17-v1-0-172beda182b8@kernel.org/