I would like a little level in the camera app, so that I can see whether my pictures are straight or not. I could use the 3×3 lines but those only work when there's a visible horizon.
You could also try to install a port of gcam (the camera app on Google Pixel phones) for your phone model. Gcam is pretty much the only camera app for Android that shows a horizon indicator when you hold your phone steady to line up a shot.
