Can anyone recommend a good app to learn ASL?

Skip apps for a bit and use YouTube playlists from Deaf creators.

Pick one beginner playlist, like “ASL Meredith Beginner ASL” or “Bill Vicars ASL 1.”
Watch one 10–15 minute lesson daily.
Pause, copy every sign 5–10 times.
Record yourself with your phone, compare to the video.
Track new signs in a notebook or Google Doc.
Aim for 20–30 new signs per week.
After two weeks, start signing simple daily routines, like “I eat breakfast” or “I go work.”