They are working in .NET 5 last time I checked. Opened an FSX script, "#r: nuget SwaggerProvider", point to a JSON API and it seems to work with IDE auto complete included with 2 lines of code, no project scaffolding, or package manager files required. Things seem to be improving on this front I guess as well.
I do agree - source generators have a better API as an implementer and can generate more than classes. I guess as soon as I need to jump into a proj file and I'm working with MsBuild anyway what stops me creating my own generation framework that runs before PreBuild that generates code for my compile step? I've done it before source generators were a thing.
I also did a quick Google search - Myriad (F# library) might be something that does something similar.
