Using freeradius-rlm-python3, at start up the following error is displayed:

Mon Aug 17 06:18:15 2020 : Info: Found debugger attached
Mon Aug 17 06:18:15 2020 : Info: Python version: 3.6.10 (default, Jan 16 2020,
09:12:04) [GCC]
Mon Aug 17 06:18:15 2020 : Warning: Failed loading libpython3.6m.so:
libpython3.6m.so: cannot open shared object file: No such file or directory
Mon Aug 17 06:18:15 2020 : Warning: Failed loading libpython symbols into
global symbol table


libpython3.6m.so.1.0 is present:

sh-4.4$ rpm -qf /usr/lib64/libpython3.6m.so.1.0
libpython3_6m1_0-3.6.10-lp152.4.3.1.x86_64

It may be that this is incorrectly linked as the file in question comes from
python3-devel:

# rpm -ql python3-devel | grep 3.6m.so
/usr/lib64/libpython3.6m.so

When python3-devel present, rlm-python3 is able to be loaded by freeradius:

Mon Aug 17 06:41:12 2020 : Info: Starting - reading configuration files ...
Mon Aug 17 06:41:12 2020 : Info: Found debugger attached
Mon Aug 17 06:41:12 2020 : Info: Python version: 3.6.10 (default, Jan 16 2020,
09:12:04) [GCC]

freeradius-server-3.0.21-lp152.1.3.x86_64
freeradius-server-python3-3.0.21-lp152.1.3.x86_64