I am trying to add support for a proprietary codec in Opera according to this question. However, my version of Opera is installed as a snap. I thus would need to know how to create a directory and copy a file into the snap folder in Ubuntu 20.04.
More specifically, the issue is that the Opera browser is installed in the snap folder and if I try to create a directory in that folder, I get the error mkdir: cannot create directory ‘lib_extra’: Read-only file system. The complete path of Opera is snap/opera/85/usr/lib/x86_64-linux-gnu/opera. I also tried to use chmod and mount-remount but I got similar errors.