One possible way is doing things that Google and Chrome don't (can't).
Catering to niche audiences (and winning those niches) gives people a reason to use it. Maybe one of the niches takes off. Catering to advanced users not necessarily a bad way to compete.
Being a feature-for-feature copy of Chrome is not a winning strategy (IMHO).
Good thing they aren't? Firefox's detached video player feature is far superior to anything Chrome has that I'm aware of. Likewise for container tabs, Manifest V2 and anti-fingerprinting mode. And there are AI integrations that do make sense, like local-only AI translation & summaries, which could be a "niche feature" that people care about. But people complain about that stuff too.
But I'm agreeing with you! These features are important to you, an advanced user. The more advanced users for Firefox, the better.