Hi,
it would seem expected that
python -c "import my_conv"

does not work, as you need to load PyTorch itself and its symbols before you load the extension, so python -c "import torch, my_conv" would likely work much better.
If you wanted to avoid that for some reason, you could explicitly link against libtorch (extra_ldflags=['-ltorch'] or somesuch).
Best regards
Thomas