It's a bit more complicated than that with the iPads. The Mini supports 5Gbps but only as USB Host mode. If you hook it up to a computer as a USB client, it'll still be USB 2.0 [0]

If you're familiar with the Raspberry Pi 4, those do the same thing. That SoC supports USB 2.0 client. The USB 3.0 host is done through an external (to the SoC) USB controller, a VIA Labs VL805. That's what the Mini and iPad Pros have done. The first iPad Pro didn't even have a USB 3.0 to USB-A cable for USB client because it didn't support it, just their host mode accessory. The newer Pros probably do the 40Gb USB4 through a similar USB controller and only in host most. Not client, where it's limited to 10Gb [1].

[0] https://forums.macrumors.com/threads/ipad-mini-6-is-still-us...

[1] https://forums.macrumors.com/threads/thunderbolt-3-cable-to-...