pip is mostly insufficient because of the C-backend and linking to libraries like BLAS. The good news is we are actually planning to drop this backend or make it non-default in the mid-near future in favor of the numba backend. If/when that happens pip install should again suffice.
For the time being you can open a request issue on the PyTensor repo asking for instructions. Do double check if somebody already opened an issue or discussion, as I remember something similar.