Restriction: this snap version works with a python in the snap environment. Therefore, we cannot use the python in /bin and modules in$PYTHONPATH. When you want to use opy with the modules you installed, please install opy from GitHub (https://github.com/ryuichiueda/opy) with the commands below. I would appreciate it if you could click the star on the repository page.
$ git clone https://github.com/ryuichiueda/opy.git
$ cd opy
$ sudo make install