This is kind of a duplicate of the paramiko issue. But, I think it could also be fixed in fsspec. I'm not sure whether fsspec does define a standard for the file object. If not, maybe it should? I find it highly unexpected that for the file object:

• seek does not return the new position
• write does not return the number of bytes written
• probably other issues?

This could be fixed here instead of upstream by adding a small wrapper around the paramiko file object. Of course, the same discussion about fsspec/sshfs applies here.