Not advice on which machine, but trust me- after about a week, you'll be amazed how much you can do with just your left hand! I fractured my right shoulder at the beginning of December,( I'm right handed) and had it in a splint till last week, so it was completely immobile. That, and hubby watching me like a hawk to make sure I wasn't trying to use it. I went from typing with one finger to using all of them on my left in a week( true, I had to proof-read & edit out extraneous letters) and discovered that pretty much the only things I couldn't do eventually, were put my hair up in a band( its very long) or put a bra on. Joking told a friend its possibly the first time hubby has put one ON me,
I really am not far off ambidextrous now. Seriously, good luck with the surgery, and the physio thats sure to follow, hope it fixes things for you.