Band-aid solution found. based on this comment here, it seems after setting the PyTensor flag, if I add the following to my script:
import pytensor
pytensor.config.cxx = '' //empty string
The code will sample although very slowly. I believe there is some weird issue in VScode as when I attempt to set the path to '/opt/miniconda3/envs/pymc_env/bin/clang++' I get stuck as before, despite this being the exact path that works and is used when I run the script in the native mac terminal without setting a path