So just to backtrack a moment, I’ll just make sure we’re on the same page – that one of the biggest issues with ANY device on Linux is that IF there are advanced features that require a custom Windows or MacOS driver, then you can basically kiss those advanced features goodbye on Linux of course. (Although there are efforts in the Linux community to address this issue to one degree or another).
So you need class-compliant devices for Linux DAW use, which is fine for many use cases, and you can frankly achieve excellent low-latency performance in my experience with very little effort. BUT you can expect to lose any special cool stuff a custom Windows or MacOS driver might have provided. So there’s the first reality check! And it’s a BIG reality check for some people.
So when it comes to class-compliant MIDI devices, some of them might still have extra options, integrations, features, goodies, etc., that might require custom software too, and those will most likely not work on Linux. So this is something you’ll have to test on a case-by-case basis.
One of my MIDI controllers, for example, is an Arturia Keylab mk3, and it’s a nice little controller. I use it exclusively via its MIDI port and basically treat it as a traditional MIDI controller, and I do NOT use its fancy Arturia integrations AT ALL. I don’t need them or care for them. I just wanted a nice synth keybed and I can do all the basic settings inside the Keylab that I need to. I have NOT connected this to a Linux DAW directly via USB yet (another thing I need to try), but my understanding is that it will work fine… but as a traditional controller only. And I will not be able to use any of the fancy Arturia features. In my case, again, I don’t care, because I already don’t use any of the fancy Arturia features. But you may WANT to use the advanced stuff of your MIDI device.
So this is the kind of thing you’ll need to test on a device-by-device basis and if you rely on some fancy custom control panel for extra features above basic MIDI i/o, then you may be disappointed.