Is there any way to mute/unmute selected tracks?
Not based on track selection
But yes, use the Mute button on the track’s Track Control Panel - see: https://manual.audacityteam.org/man/audio_tracks.html#panel
You could temporarily “mute” selected tracks by turning them to silence with Ctrl+L - and then restore them with Undo - but you wouldn’t want to do anything else in-between as Undo is not selective, it woks backward through each command one at a time.
WC