Different highlighting between foldtext and "the line number on the folded line"?

Question

Can I control the highlighting of the foldtext separately from the color of the line number on a folded line?

I want the foldtext to be quite visible while keeping my chosen line number color

Answer 1

I'm afraid this isn't possible. See :help fold-colors:

The colors of a closed fold are set with the Folded group hl-Folded. The colors of the fold column are set with the FoldColumn group hl-FoldColumn. Example to set the colors:

:highlight Folded guibg=grey guifg=blue
:highlight FoldColumn guibg=darkgrey guifg=white

The Folded group encompasses the line number; no further configuration than the above is available.

There is currently an open issue requesting a way to achieve what you ask for, so the Vim maintainers are aware of the problem.