Hard to believe any VPN company provides serious protection from the American government. In the highly unlikely event that the company won't cooperate they can just comprise you outside that channel. See everyone who thought Tor was enough to evade the US government.

I trust Mozilla to not cooperate with anyone less powerful than Uncle Sam which is a lot more than most shady fly-by-night VPN operators.

If you're using your VPN as protection against your ISP, wifi provider (internet Cafe, school, workplace, home), or some other MITM you're better off with a service run by a serious company, with a lot to lose from a scandal and a long track record of not lying and being technically competent.

If you're looking to hide your browsing from the US government you should a) give up or b) definitely not use a commercial VPN.