You can solve it at least partially by installing some (scripts, patterns, brushes) of the gimp-data-extras, which were not included in 2.10
The one you want to download is the latest: 11-Jun-2018 14:51 4.3M
gimp-data-extras-2.0.4.tar.bz2
https://download.gimp.org/pub/gimp/extras/
I'm using Linux and scanning via sane.
The gradients entry I had in 2.8 included only custom gradients AFAIK.
Buttons had 2: Simple button and beveled button.
Other entries: Brush from text, web page themes. No idea how to get these into 2.10, never used them.