My Mac mini has USB4 and thunderbolt, but I don't have anything to take advantage of it. The hub I have with a NVMe and a SSD drive in is 3.1. It is fine for me. I did look at external thunderbolt/USB4 drives, but the prices are crazy
Yes, the complexity of going as fast as 40Gbit/s increases the cost; not bad inside the computer (which as a Mac user you don't have that choice) but a lot more expensive externally as its much more complex.
The USB numbering is broken, the committee went mad. They now expect people to use the data rate.
A useful table, and comment:
https://www.tomshardware.com/news/usb-3-2-explained
The version numbers are confusing and don't mean much, as USB 3.0, USB 3.1 Gen 1, and USB 3.2 Gen 1 are interchangeable and operate at 5 Gbps, while USB 3.1 Gen 2 and USB 3.2 Gen 2 are the same and operate at 10 Gbps.
My laptop (MS Surface Pro) has USB 4 (40 Gbit) and USB 4 supports Thunderbolt devices. The same era of CPU desktop only supports 20 Gbit (USB 3.2 Gen 2x2).
0.5 Mbit (USB 2 speeds from late 1990s)
5 Gbit (max over type A port)
10 Gbit
20 Gbit
40 Gbit
My Mac Mini M1 internal SSD is only 2.8 Gbit/s capable, similar to my Surface Pro laptop. The desktop PC has a PCIe 4 NVMe that does about 8 Gbit.
So really unless you have an external RAID array for some high end video work, then most of us would be happy with a 10Gbit port for accessories. iPhone 15 Pro was first that supported 10 Gbit. The iPad Pro range was faster. The standard iPhones only do 480 Mbps even on a USB-C port, as Apple seem to expect everyone to use WiFi.
26 years of broadband connectivity since Sep 1999 trial - Live BQM