You can't(as a single company/entity) find a work around something like this. Proton had a court order from the country they operate from. You can fight court orders but you can't usually disclose them(gag orders and all).

The only reasonable way(i can think of) to make it a bit harder for this to happen would be to have a second(and maybe a 3rd)unrelated entity/company in an adversarial country that you can use as a relay. In this case use it as a VPN service to access the e-mail on Proton servers.

Anonimity is inconvenient these days... and next to impossible if any govt agency is out to get you. The only way you can make it hard(er) is to spread over multiple jurisdiction and rotate accounts/discard them after a few uses. A system similar to one time pads of sorts combined with PGP.