Hi, sorry for the very late reply as I was trying to resolve the issue on my end.
I believe I’ve sort of resolved the issue, apparently for whatever reason the NVCC didn’t trigger for the 3DSSD repo which I was focusing on, but instead it triggered when I tried to install the module from original pointnet2 repo which it originally referred to. If I have to guess, it’s likely caused due to either:

The pointnet2 library within the 3DSSD repo had perhaps missing bindings (?), or
The library in the 3DSSD repo was structured such that the C++ libraries bindings weren’t   detected during the setup.py install for the pointnet2 library.

Unfortunately, due the code originally written using a much older version of PyTorch (v1.0, vs v1.7.1 that I’m using), I apparently still wasn’t able to build the module from the pointnet2 repo.
However, I luckily checked back and found that apparently the pointnet2 repo itself referenced to an even earlier implementation of the Pointnet2 kernel by Erik Wijmans 1 that has been updated to support the later versions of PyTorch. This repo seemed to have the structure & functions updated properly to later versions of PyTorch so  installation went smoothly without any problems for me.
The pointnet2 repo by sshaoshuai are noted to have included some kernel-level which are claimed to improve the speed of the pointnet2 functions though, so I decided to try and combine the features from that repo into Erik Wijman’s implementations.
Fortunately this apporach seemed to work for me, and now I’m able to run the training on the 3DSSD Repo, which ultimately was my goal. I’ll perhaps try and update sshaoshuai’s implementation so that it’s compatible with the latest versions of  PyTorch (similar to how Erik  Wijman’s implementation works fine for me) seeing this experience, once I have the time.
Thank you once again for the help/suggestions that I’ve received so far (in particular regarding the NVCC and how the CUDA compiler works) though, and I’ll update if there are any other problems that I encountere again in the future for this issue.