Under "Audio & Visual", "background sounds" is a built-in 'white noise' generator and can be useful for relaxing / sleeping. You wouldn't want to leave it on all the time, of course.

Under "Touch": "Back Touch" lets you map a double/triple tap on the back of the phone to various actions.

There's a lot of other neat features in iOS Accessibility (eye-tracking control! automatic captions! sound recognition!) and I'd encourage you to poke around to see what's available.

I find it acts a little like being able to see the cursor on a desktop or laptop; it provides a little bit of immediate feedback that the system recognized your intent, and helps make it clear whether it's the OS or just the app when things are getting laggy.

I wish my Pixel 9 had it but I guess it hasn't trickled down yet. I think it's in the latest Android on latest Pixel devices though.