Apologies about the unsolicited PR. I hope this helps.
Adding Catppuccin themes from: https://github.com/catppuccin/fish
They note:
Q: Where's the Latte theme?
A: All three themes contain Latte as the light variant. Install any of
them, and then set your system or terminal theme to light mode.
Not sure about Fish Shell policy to keep them up to date here, I hope
this is not a nuissance.
Closes#12299
c2f7c5fbeb