If you visit the Early Music Shop at some stage, might their small portative organs might also be worth looking at? The right hand plays the keyboard, whilst the left hand operates the bellows. Needs a bit of pressure from the hand to play evenly, but not that much: 'weight' rather than 'pushing'. The EMS's smallest version (1-foot diatonic) has a nifty left-thumb-strap, which I find reduces the amount of work needed from the hand when inflating the bellows.

A gorgeous instrument although, alas, a good one can be expensive and the small EMS model needs significant retuning if you mean to play it seriously.