You could always hold squat position while leaning against the wall, and also lunges are good, work similar muscles (but aren’t exactly the same, so be aware).
The box squat! It’s possible to modify to suit anyone, and progress can be achieved by switching to a smaller box or chair. Basically it’s just sitting down onto a chair or box (with the right technique) that’s just low enough to challenge you, and then standing up.
Also I’d recommend hip hinge-type of movements, as they can be used to significantly strengthen the back chain (back, glutes, hamstrings). Here are 2 great videos: https://www.youtube.com/watch?v=fckVcvFaT4w