I've added "Remote Control" via a pull request — a feature I found useful in Clementine but missing from Strawberry.
I started this project in November last year and believe I followed the contribution guidelines.
I have now completed functionality that covers my needs: remote control of the player including playlist management.
I've also written Linux and Android clients, with the Android client currently going through Google Play certification/publishing.
As I haven't had a response on the PR in a while, and I'm not sure how best to move this forward. It's possible nobody else needs this feature, but as far as I can tell it's opt-in and shouldn't cause any harm to have available.
I would like to contibute more to Strawberry, but am unable to do this until this is resolved.