I've never tried the KDE connect thing but I'm guessing that it uses MPRIS2 to Strawberry and also have a service running which listens to a port which then function as a received on the computer which again the Android remote connects to.
All such remotes which uses standard MPRIS2 will function with Strawberry.
But they only have basic functionality: https://specifications.freedesktop.org/mpris-spec/latest/
The purpose of having a custom remote specifically for the Strawberry like Clementine does is to manage all features of the player, not just basic play/stop/pause, etc. It won't be compatible with other audio players.