There are some great chair exercises including light weights to exercise with yours arms and use a big socks to put some small water bottles in to drape over your ankles to do some exercise for your legs. Hope this helps.

Check with your Doctor or therapist as to what will help. Or goggle your issues,

Buy a cycle exerciser that you can use sitting for your legs or on a table for your arms and upper body.I got mine in Lidl,so it was reasonable enough.It had proved invaluable on the days when I’m off colour.
Good exercising
Sean

I have orthostatic tremors...rare disease...can’t stand with out shaking ....have to sit no tremors then.....so this past month I bought a bike...I can ride no wobbling as long as I pedal.