What typically is happening is that a wheel package was missing. When that happens python tries to compile the package, to do that it requires extra dependencies, such as compiler, python-devel, and other *-devel packages, because they weren't available it failed. This is very common when a new major version is released, it requires authors of the C based packages to build wheels to make installation easier and not requiring extra dependencies.
Looks like Pillow has wheel for 3.8 now since April 2nd, so might work now (no compilation is needed). I don't know other packages so can't check them. Psycopg2 would probably be another one with this issue (also fixed on April 6th).
Looks like Pillow has wheel for 3.8 now since April 2nd, so might work now (no compilation is needed). I don't know other packages so can't check them. Psycopg2 would probably be another one with this issue (also fixed on April 6th).
[1] https://pypi.org/project/Pillow/#files look for cp38 wheel files.