The answer is nothing, because a browser without significant adoption is bound to have some inevitable issues. I've tried Orion, for instance, but the fact that

The answer is nothing, because a browser without significant adoption is bound to have some inevitable issues. I've tried Orion, for instance, but the fact that 1Password is not signing extensions so that IPC works on these browsers (rightfully so, because it'd be easy to grab your entire vault) already makes it not worth considering. It also would likely need to be proprietary, because selling binaries doesn't really work too well if your product picks up steam. Which then conflicts with the privacy promise. Ungoogled Chromium is probably your best bet.