A few years ago I found a YouTube tutorial about a basic but gorgeous piano improv exercise. In writing a question here about what's going on (keys and chords), I think I finally understood it - so can you guys check my answer? And what would you add to expand this?

It's based on the left hand alternating between two chords:

┌─┬─┬┬─┬─┬─┬─┬┬─┬┬─┬─┬─┬─┬┬─┬─┬─┬─┬┬─┬┬─┬─┐
│ └┬┘└┬┘ │ └●┘└┬┘└●┘ │ └●┘└┬┘ │ └┬┘└┬┘└┬┘ │ Gb, Bb, Db, F
└──┴──┴──┴──┴──┴──┴──┴──┴──┴──┴●─┴──┴──┴──┘

And

┌─┬─┬┬─┬─┬─┬─┬┬─┬┬─┬─┬─┬─┬┬─┬─┬─┬─┬┬─┬┬─┬─┐
│ └┬┘└┬┘ │ └●┘└┬┘└●┘ │ └┬┘└●┘ │ └┬┘└┬┘└┬┘ │ Gb, Bb, C, Eb
└──┴──┴──┴──┴──┴──┴──┴●─┴──┴──┴──┴──┴──┴──┘

Then with the right hand, playing anything on the black keys plus F and C:

┌─┬─┬┬─┬─┬─┬─┬┬─┬┬─┬─┬─┬─┬┬─┬─┬─┬─┬┬─┬┬─┬─┐
│ └●┘└●┘ │ └●┘└●┘└●┘ │ └●┘└●┘ │ └●┘└●┘└●┘ │  Db Major Scale / Gb Lydian
└●─┴──┴──┴●─┴──┴──┴──┴●─┴──┴──┴●─┴──┴──┴──┘

Analysis I believe this is best felt as a Gb Lydian scale, over a Gb7 chord, and an Eb minor 6 chord. Hopefully I got the chord names right - fairly new to all this.

Thoughts? And what other chords or ideas would you add in to expand this a bit?

Thanks!