SATB - play certain voice(s) and mute others

What might help here is #58031: Dynamics/hairpin range for Voice.
You could also generate parts, each staff twice, and in those parts make one voice silent via right-click on a note select, more, same staff, same voice, then untick play in inspector

Won't F10 allow ?

Actually you can do this although the procedure might look a bit weird.

The idea (found here in Polish forums) is to use a different instrument supporting multiple channels and to assign different voices to those channels using staff text properties. This will make them effectively appear as separate entries in the mixer/F10.

Currently only trumpets and strings have multiple channels: e.g. trumpets - normal/mute (2), strings - normal/pizzicato/tremolo (3) but one could create an instrument with 4 channels as well.

Follow the instructions in the handbook for more visual explanation: How to change instrument sound midway through score but apply to the first note of a staff.

I have the same problem.
The ideal solution would be to be able to assign different instruments for the voices in a staff. SATB scores usually use one staff for SA and the second for TB.

The same applies to the extraction of voices: also here it would be helpful to allow the selection of voices in the staff.