Hi Rider45
You might feel "alone" on this one as almost nobody are using theme outside of the native themes of GIMP.
If there are people using them, they will come, but have patience.
A suggestion while waiting for some one who has the theme you are speaking about,
Why don't you use the native dark theme or the system theme if your system is in Dark mode? (Edit / Preferences / Interface / Theme)
There are 4 themes (did you tried them?):
Dark
Gray
Light
System
Below "Theme", in the preferences you have "Icon Theme", here as well you can chose "live" the type of icons you want
Below "Icon Theme" you have "Toolbox", there you can un-tick "Use tool Group", you can drag 'n drop a tool above or below another tool, etc.
And don't forget, the themes you are actually using, might not be very used, so very few people might have it, thus have patience that one of these person sees your post
Have a great day