This app was mentioned in 3 comments, with an average of 1.00 upvote
The one I have installed at the moment is simply called Spectogram. It's okay, not spectacular.
Tonalenergy also has a pretty good spectrogram built in. It's not free, but I think one of the best apps for musicians on the Play store.
All you're doing in Audacity is decoding the spectrogram into the •'s and –'s. A quick google search produced this app for Android. Just look for anything that allows you to view the spectrogram and you should be good. Once you've got the •'s and –'s you can punch them into any online decoder to get the text.