I imagine this is already achievable with the sf2/z player/s on the platform, but a dedicated mellotron plugin would be beautiful!
It could just be that I’m more attuned to it now, but it seems that there are more and more new mellotron VST plugins and hardware devices with each passing month. Or perhaps it’s both! Either way, I suspect I wouldn’t be the only one who would get some use out of such a plugin 
The ist a nice mellotron patch for the organelle: Mellowtron | Patchstorage
It is written in pure Data - so in theory it should be possible to Port to the dwarf…
Maybe with significant rewriting and using camomile, but since a mellotron is really just a sample player creating it around an sf2/z player sounds like a much better approach.
@dreamer You are right. Just take the samples (see the link I posted) and put a tape sim behind the player for optional wow/flutter.