You would use belts to get "endless" faders, to avoid motorized restore?
I guess people who like it tactile, prefer to feel the position of a
fader knob and btw. we likely want that it appeals to all senses, IOW we
also want to see the fader knob positions.
Regarding to wheels also keep in mind, that faders could be very long
but for an "endless" wheel you perhaps can't do the whole fade by
keeping the finger on the wheel, you perhaps need to set back the finger
to continue turning the wheel.
Btw. for faders knobs you could use fader bridges, if you want to use
group of faders ganged.
JFTR you could optimize such a mixer to your needs, that is the
advantage of DIY, but DIY likely is more expensive and a lot could go
wrong. OTOH if restoring the position shouldn't be needed, replacing the
short faders of a nanoKONTROL with long faders might be possible and
would cost less. I wonder if longer faders would be useful for the 128
MIDI steps.