I’m not aware of a solid centralized place to find high quality, multi-app color schemes like these.

maybe, we should make a lemmy community, with all color themes, and something like 1 post for 1 color theme. in the comments, we can add various places (or ways) you can use/install them, and maybe a weekly/monthly post, to rank the best themes of the months (rnaking all existing posts by activity in last x amount of time).