There are times when I need to work out or practise some right hand treble, but my PA - even the little FR-1x - is too heavy or awkward for the circumstance, for example sitting (parked, of course!) in the car driving seat, or lying abed. Trying to play one of those accordion apps on an iPad screen doesn’t work for me - spacing all wrong, and no tactile feedback. What does work though is hooking up my three octave iRig midi keyboard (full size, velocity sensitive keys) to said iPad and rotating the keyboard so it fits between my chin and my lap in the normal accordion treble keys position. There is an iPad app called ‘Vintage Accordion’, which is reputedly sampled from a nameless Castelfidardo instrument of the sixties, that I use. As apps go (as opposed to computer programs), it is a little pricey at £9 but the sound appeals to me and it works well with midi. Even with a pair of headphones added, the whole thing weighs very little, and is extremely portable. No bellows effect of course, but the velocity sensitive keys provide for some variation of expression, and this is a only a practice rather than a performance tool.