Interesting you mention this. @marcan42 just did a stream on porting a Pioneer DJ mixer to Linux, so that might be an option.
https://youtu.be/cUVuTBH51GY
I think most of them are MIDI and will work with Linux; it's just that some Pioneer ones use nonstandard audio descriptors (you can use the control surface but not the audio outputs without a patch). You may have to write your own mapping for Mixxx though :)