Naemanson,

Sure you can. It would be pretty easy. Remember that a Lap Dulcimer is traditionally played with a Noter. A dowel like slider that you move up and down the melody course of strings. Finger fretting on a Lap Dulcimer is a relatively modern technique.

Autoharps are heavy but there are many ways to support the instrument. I would remove chord bars rather that add them. A little more spacing between bars may be easier to play. But that would be learned by trial and error. And ultimately not really acceptable.

Keep trying, keep playing. Good luck

Don

(I have a good idea what your issues are. I can tell you honestly if I had to have my same injuries again and the only choice was which hand to damage, it would be my right. With my remaining facility I could hold a flat pick alright and frail a banjo but fretting the guitar is very difficult.)