HI< awhile back I knew a guy that had a stroke and lost use of his one side(don't recall what side however)
But he worked with a CAT dealer, and they some how set up a new skid steer for him,(he bought it set up from them, around 2016 or so) and was a skid steer not a track loader, but more or less same deal I would think)
they set it up so he could use it with just one hand/arm!, which I gather is what you also need!
SO, I would maybe suggest try talking to a GOOD long standing Cat dealer near you, or other brands, or maybe even just a multi heavy construction equipment repair shop, thats been about a long time!
reason I say been about a long time in the business, is as IMO< most dealers that have been around a long time, seem to have way more knowledge and knowledgeable service techs, that have seen more things over there time at the dealer ship/shop , improving your odds of finding some one that maybe crossed this bridge before! and is MAYBE more willing to work with you, due to they been down the road before,
I am sure many might be brand loyal, so, finding a universal fitting, ??
might not be in there favor, and will maybe push there BRAND on things, but I doubt it really matters,as long as you get the result you need!
so, this would be mu suggestion
if you know any really sharp techs, , you might also try reaching out to one and seeing what they suggest too
as they again, may have some insight that can help you here, best of luck to you