https://mullvad.net/en/browser/
Do keep in mind Sweden, Mullvad's country of origin is
part of the 14 eyes.
However Mullvad is generally respected by privacy advocates for being one of the only VPNs to require no personally identifiable information on account setup, generating a key that can be thrown away after you don't want it, You can also pay for it via Cryptocurrencies such Bitcoin,Bitcoin Cash, Monero, and you can even send them money by mail. You can also access their services via Tor.
Now in regards to the browser itself:
The Mullvad browser seems to be a fork of the
Firefox Extended Support Release Browser and it also seems to rely on a few Tor browser features.
For example the Mullvad browser is able to Reset its fingerprint the same way the Tor Browser is able to reset its fingerprint
In addition to that it comes with the following extensions:
It seems to have removed a lot of firefox's features such as the default such as sync, and pocket, not that i think anyone is going to miss the latter. Firefox telemetry seems to be completly disabled or even removed
In addition to that there seem to be different choices in regards to search engines, as in DuckDuckGo(which should frankly not to be trusted after the stuff they pulled) and Mullvad leta which i am unable to access since you can't connect to it without the mullvad VPN, but i assume is possibly some search engine reliant on opensource code such as
Searx.
Finally you will find that all history and logins along with cookies get completely deleted after the browser is turned off. However if you wish to re enable them you need to first turn off the "Always use Private browsing mode under Settings > Security and Privacy > History. Obviously do keep in mind that this will severely diminish a lot of the security features of the browser. And disabling some of these features would be pointless anyway due to the fact you will frequently change fingerprints. It could however be useful if you want to keep browser history.