Music production on iOS and Android generally cheaper than on PC. With a decent tablet you can make decent stuff. Example of musician using only mobile apps to make music is @jessieyun0404. Go and check out her music!

DAW

Caustic (Android)

GarageBand (iOS)

Music Studio (Android)

FL Studio Mobile $15.99 (Android/iOS)

SunVox $5.99 (Android)

PixiTracker 1Bit (Android)

NOTATION

MuseScore (Android/iOS)

Notation Pad (Android)

INSTRUMENTS

iSymphonic Orchestra (iOS)

Syntronik (iOS)

EFFECTS

AmpliTube CS (iOS)

AmpliTube Acoustic (iOS)

If you know more apps please add below in the comment, I'll add them here and credit you!

Happy music Making!