Both MTS-ESP Mini and Master support loading .scl, .kbm, or .tun files, so it really is intended to be a full solution for microtuning.
As far as Linux goes, I don’t know what to tell you. While it’s definitely noble to support Linux, forcing full parity with Linux versions seems artificially limiting.
BTW, when I added support for MTS-ESP in a plug-in I worked on a few years ago, the whole process took about half an hour, in case that’s encouraging!