You can manually remove all of the previous drivers and their GL32 counterparts, your flatpaks will still run as long as you have the newest drivers.
I’m not sure why they don’t get caught by the --unused flag, but they are definitely not needed from the flatpaks I’ve tested with.
I remember a year or so ago when I switched from Pulseaudio to Pipewire, best decision I’ve ever made in my entire life!