I think it's worth mentioning the caveat, that it doesn't natively support PWA in the same way WebKit browsers do. It has little to no support (depending on your definition of support).
If you subscribe to cable/satellite television, you expect there to be advertising. I'm not certain, but i suspect the agreement you sign while signing up for cable or streaming services, would include some sort of advertising clause.
Ie, u less a service explicitly promotes am ad-free experience, there should be no expectations of such.
I use PWA apps regularly. Once that feature is available and capable, I'll gladly run to the Firefox team.