No, I have not opened a bug report on OpenSUSE. Since the OS uses bi-arch throughout, using lib64 is the natural thing to use for libdir on the OS.

I think the issue lies with getpath.c only, since it makes an assumption about the libdir config value, which doesn't necessarily hold in practice. The libdir config value can be changed via the standard --libdir configure parameter, so getpath.c should really not assume that the default setting is always used.

Having a variable in Python 3.9 is nice, but perhaps we can still make Python 3.7 and 3.8 work as well.

The correct approach to building the full lib_python path is not to use exec_prefix + "/lib/python" + VERSION, but instead to use libdir + "/python" + VERSION (which corresponds to the Makefile variable BINLIBDEST). libdir would have to be taken from the config variable LIBDIR.