Preamble: keeping a service like Proton running requires money, and as there are no ads it is obvious it must come from subscriptions.

There are already multiple proposals regarding a bridge plan:
* including it in the free plan
* a barebone plan including just the bridge and the signature removal
* once-in-lifetime payment
* 1$/month Bridge subscription
* Bridge only plan

So IMHO it would be interesting to have a plan regarding only the bridge, for those who don't need/don't want/can't afford a more comprehensive plan, but would still like to contribute and have an extra feature

Be it a monthly/yearly subscription, a once-in-lifetime payment or else, this is a decision that should be made by the Proton team: this would require more resources usage, and these aren't free