About a year ago, I logged a feature request on the sfizz[1] repository for MPE support. My main interest is in arbitrary per-note microtuning (e.g. just intonation, where notes may be raised or lowered by a syntonic comma). Why sfizz? I like the sound of wobbly tuning, particularly on pianos, where we expect absolute consistency.
A few days ago, to my surprise, somebody had forked sfizz and done it! [2] Mostly – it took a couple of back and forth iterations, but it’s now working. (Note: it’s experimental, not deeply tested, and not merged into sfizz mainline, but I’m running it without crashes here.)
To use it, you’d need to build yourself – 1/ clone --recursive from rullopat’s fork of sfizz-ui; 2/ checkout the mpe branch (both on sfizz-ui, and on the sub-repository stored in the library/ folder); 3/ follow build instructions at Build - SFZTools .
A demo – I’m so happy after a few years without them to hear those syntonic commas again!
(Some years ago, @Spacechild1 turned me on to the VST2 version of sforzando, which is one of the very few plugins to use the detune parameter in the VST standard [but, VST2 = outdated, unsupported]. Then it became impossible for VSTPlugin to maintain its own wine bridge, so I had to switch my wine plugins over to yabridge, and yabridge drops the detune value 
so I lost that functionality for sampled instruments for a couple of years. Now I can get it back, using MPE’s per-channel pitch bend.)
hjh
[1] sfizz: open-source sforzando player, SFZ Tools · GitHub