[Darryl Ramm]

And be careful here which Thunderbolt version you are talking about.

The Mac Pro trashcan have Thunderbolt 2
The new Mac Pro Cheesegrater (i.e. 7,1) has Thunderbolt 3.

Thunderbolt 3 hopefully has a long compatibility future, because of its adoption into the USB 4 standard. Old Thunderbolt 1, 2 are just slower, esp. for use with fast NVMe storage (and storage is a weak point of the whole Trashcan bad design), and has lower-end video display capability--but not an issue for audio interface use.

Thunderbolt (1) and Thunderbolt 2 are very compatible with each other. Thunderbolt 3 is often compatible, with 1 and 2, via an adapter, but you have to pay attention/check for the specific device.

Some Thunderbolt 3 peripherals will *not* work on Thunderbolt 2, especially Thunderbolt 3 fast PCIe/NVMe disk drives. Audio interfaces are likely to be compatible using an adapter like Apple's Thunderbolt 3 to Thunderbolt adapter, and you can often use that bidirectionally to go from 1,2 to 3 or 3 to 1,2. Thunderbolt 3 peripherals that are bus powered are more likely to not work. Many Thunderbolt audio interfaces will be compatible with different versions of Thunderbolt using the Apple Thunderbolt adapter, but you should.

There are other Macs with Thunderbolt 3 at much lower price points than a Mac Pro, including Mac mini, iMac, and MacBook Pro. But all depends on your needs.