I have been working on moveable-do ear training for a while now. I would like either a keyboard app where you can change the pitch of the C note or an app that will let you play some kind of solfege representation and choose the pitch of the Do.
The idea is that I hear a melody and I think I correctly hear it in terms of notes of the scale, but I want to check myself. But I don't want to have to deal with verifying it by picking it out on a piano keyboard and also transposing in my head between different key signatures. Ear training is hard enough without dealing with that.
I have periodically searched for something like this on the Android app store or web and cannot find anything.