Good on you for continuing to play! I am younger than you, but started getting some left hand arthritis pain a few years ago. When I ran across a good deal, I picked up an inexpensive square neck resonator guitar (not a Dobro brand) to start messing with, prepping for that eventual day when I might not be able to play finger style any more.
You can simulate the idea by using an extension nut, like this one from Elderly Instruments, and many other sources.
https://www.elderly.com/guitar-exten...erfect-nut.htm
I would also support the idea of a baritone uke. You can go one step further and tune it DGB
D which is the high four of Open G tuning, and play most every chord as a barre, assuming that still works for you. If you are not trying to maintain a particular chord shape or "grip", it is possible to use an extra finger supporting the barre finger. I've actually used this technique on a regular tenor ukulele with a couple of students who had really bad arthritis in their hands. They were delighted to be able to strum along. And if your right hand is doing better it can handle the fingerpicking part instead of just strumming.