Turns out that I was actually missing some packages in my Visual Studio installation & that changing the project settings like mentioned in my previous post really just lets me use packages that I had in an older VS installations on my system.
So the long term solution is to go to the “Visual Studio Installer” and make sure you have everything thats needed (and the correct version of everything that is needed, as Unreal Engine can silently refuse to use packages that are slightly off in the versioning)