I confess that I haven’t really done anything other than almost constant decluttering, but my friend who has RA has done quite a bit. She started by turning her downstairs loo into a shower room in case she’s confined to her downstairs rooms. Then she replaced her old kitchen with a new one, where her oven and microwave are more accessible - she’s bought good, lightweight cookware too, ditching all the heavy stuff. A bit of a disappointment, as she wanted her front door changed to remote control by fob, but at the last minute the company said they’d misled her and couldn’t do it. I think they were dishonest, but she went ahead with their expensive alternative.
Upstairs, she’s refitted her bathroom with a walk in shower and one of those Japanese loos, which does everything.
Definitely not small, inexpensive tweaks, but she’s happy with the results.