I found this nice tweet about the FortGL library for software rendering:
The FortGL library can be found here: GitHub - lewisfish/FortGL: Software renderer in pure Fortran (cc @lewisfish)
The 3D programming course referred to in the tweet can be found here: https://pikuma.com/. The courses offered look quite fun and engaging. The author of the courses is Gustavo Pezzi - a university lecturer teaching computer science and mathematics