I slept on this and I think I agree with you more now, a “pool” would of course be handy for trying out alternative melodies etc.
If I came up with something “out of theme”, I’d prefer the tab for a new song though.
Anyway, I have an idea how this “pool” could look like and I’ll hopefully post a mock-up later in the other thread regarding this.
Edit: Done! https://forum.renoise.com/t/pattern-pool-toolbox/42238