Yes, if you want to watch something on multiple platforms, then it's best to not sign up through a platform payment system since those lock you into that platform.
With some content companies, it is possible to kind of hack them into general use like:
Go to content website
Do a "forgot my password" and create a new password
Log on via other platforms using that new password
However, I suspect that it is possible that this may create problems and confusion later. For example, a platform payment system might need the password it created to keep the account current. ?? (I don't know.)
I did this with P+, but only after letting my Roku paid subscription fully expire so that Roku's payment system was no longer involved.
Banned but back. Because why not?
