The issue is not caused by CUDA or Python, but by the size of the pip wheels and conda binaries.
Since the pip wheels have an especially hard memory limit, older compute capabilities are removed after some time, which was the case for 3.5. The current CUDA10.2 binaries support compute capabilities 3.7-7.5 and the CUDA11.1 binaries 3.7-8.6.
EDIT: you might also want to check this issue 9 where some users were building binaries for sm_35.