What’s still missing from LEGO apps?

I’m validating an Android/iOS app idea for LEGO collectors. Not selling anything and no links here — I just want to learn whether the problem is real. The core idea is one mobile place for: sets you own sets you want missing pieces notes / storage maybe purchase price + value If you already use Builder / Brickset / Rebrickable / BrickLink / spreadsheets, what still feels annoying or broken for you today? Even one concrete example would help a lot submitted by /u/NervousVariation2807 ...