These suggestions assume the use of feet, if this is not helpful then please contact OHMI.
‘Cello
Use a floor stand to support the instrument and a bow holder to provide a toe grip on the bow.
Electric Guitar / Bass Guitar
Support a standard Guitar or Chapman Stick on the floor and use the toes of either or both feet to select the notes.
Ukulele
Toes could be used to play an Artiphon Instrument 1. Full chords will sound in ‘Smart Strum’ mode with one digit on each side.