I totally agree with your idea of practicing harmonics in different scales! It’s not a bad idea to practice playing chords of harmonics as well. A little trick I devised is to use enharmonic flats if you get a three-note chord of harmonics with a sharp in the middle or bottom. Your palm slants upwards, so the flats come out nicely. You would have to break your arm to slant the hand down to produce those harmonics well. I also only play the regular harmonics that split the string in half. The others don’t sound good and I have never seen them used in a piece.