How do you want it?
I happened to want a 60W Midi piano for easy use at events.
Depends on what you will genuinely use it for. The problems you describe are precisely those of the ongoing development but it is surprising what you can do with GPIO to power encoders. What you also loose is the s1-s4 switches which serve as a very useful control midpoint between the encoder world of znthian GUI parameter displays and the free for all world of MIDI devices. . .
I’ve not seen a GPIO implemetation of the the S1-S4 switches which indicates that 12c zynaptik type connections are a way forward.
If the application you have in your head involves use of these switches then this is something to consider. I use them for Record,Playback for MIDI and audio configured as toggled.
LCD screens are a hell all of their own. The closest I got was another Pi3 build with a Waveshare touchscreen which ws a saga all of it’s own…
https://discourse.zynthian.org/search?expanded=true&q=%40wyleu%20Waveshare
Not sure what you mean by this.
There is the zynaprik card
and I’m sure @jofemodo would be happy to supply encoders as well! But you can certainly run a zynth without encoders. A mouse and HDMI will provide a working solution.