A theme I hacked together for GIMP 2.10/xx to meet my needs. You might like it. You might not. Give it a shot.
Personally, I find it much better than the default themes/layout that comes with GIMP.
This is a tweaked version of the Orange Hints Theme by migf1 over at;
https://www.deviantart.com/migf1/art/Clearlooks-Gimp-2-10-Color-Hinted-Themes-v1-2-1-846265163
The theme is found in the gtkrc file & the layout for GIMP that I use is found in the sessionrc file.
Given how wonky FOSS can be, it might not work for you for whatever reason, but it will make a great starting point if you want GIMP to look 100x better.
Enjoy!
Scott - Robot Nerd from Outerspace.