It sounds great, sadly I think Facebook can generate much more by showing you advertising.
1. https://www.statista.com/statistics/251328/facebooks-average...
Eg build new products that work with Facebook and sell them.
An ethical Facebook may find it could enter new markets.
https://www.cnbc.com/2020/11/03/facebooks-average-revenue-pe...
That said, I definitely believe that collecting subscription money would not stop them from trying to collect data about you, for advertising purposes. They'd view subscription as just a new revenue stream (yay!).
Facebook will never stop collecting data on its users as long as it exists.