It's a bit clunky, but the only real solution is just "a computer" with an old Logitech K400 keyboard + mouse combo. You won't be "casting," (although I suppose you still could) rather you'll just be using the keyboard directly. This is low tech but also sort of "bomb proof." A company can't sweep the rug out from under you, your setup will always work, and given that it's literally just a computer running whatever OS you want, you can perform nearly any task with this device. You might complain "but my embedded [company] product does X." Yes, but that product will be dead in two years, and they'll keep making the UI worse, and injecting more ads. Your computer will just keep working, and changing only as much as you let it change.