There’s a few available from this company for classic synths. They are available DIY as well.
The Prophet VS one and the software control panel are quite useful. Automation for VS 
This is awesome, why did i ever have missed this ?
I don’t know, I guess its niche stuff. I only found it because I was searching for ESQ1 videos on Youtube.
I like how with the VST plugins you can automate things like wave in the ESQ1 in your sequencer. Almost like wave sequences.