Hanging from a pull-up bar, or doing pull-ups, is a great way to work grip strength and other things. I haven’t done those in years, because I have no access to a pull-up bar.
The type of grippers I use are Heavy Grips. They’re totally different from the cheap, weak gripping devices you’ll find in sporting goods stores. These are for hardcore grip development. You do not want to use high reps with them, and you don’t want to train with them more than two or three times/week. They are not designed for high reps. If you can easily squeeze the handles together ten times, you’re ready to move up to the next tension level. I have Heavy Grips for up to 350 lbs of pressure, but am still working on the 200 lbs one (which isn’t considered too high up for hardcore grip enthusiasts, but is still quite hard for the average man). I won’t even touch the 250 lbs one (the next one up). Many years ago, when I started using the Heavy Grips (at the beginner level), I tried too much too soon and got tendinitis in the palms of my hands. It took about a year or more before I dared try the Heavy Grip again. I learned that less really is more. These grippers also give your fingers calluses; they are not comfortable to use when you first start using them; they have a rough, knurled texture. I work as a professional massage therapist (or I did, before Covid), which in itself also strengthens your hands and body, and training with the Heavy Grips made a noticeable difference for me.
I used to incorporate fingertip pushups on the floor, especially with cat stretch-style pushups, but no longer do that. There are several things I used to do that I simply dropped as I’ve gotten older and my motivations have changed. It’s good to start on a wall like you are doing. Looks like you have a good routine going there.