MPE is possible for sure, there is zero technical reasons why it would not be.
The MIDI decoding and message passing steps are all fine, LV2 format and plugins will receive the MIDI bytes as-is unaffected and all that.
It is just that we do not have a single plugin that supports MPE in the plugin store right now.
So yes, it is all possible and in a way “supported”, but the plugins are lacking on this area.
I have helped a bit to make Surge working as LV2, but didnt work so well. Their next iteration, labelled Surge XT, is switching from custom code to JUCE, so an LV2 version likely to become official.
Surge, Vital, and other open-source synths that support MPE are very complex beasts though, the porting process to the MOD platform would requite a lot of work for which we do not have the resources to allocate to right now.
One thing that brings me hope is running JUCE GUI code directly on the browser.
This demo page is pretty impressive Emscripten-Generated Code
So perhaps we can reuse the full desktop GUI of a few plugins… that would save 95% of the porting work for JUCE based plugins.