Help Me Break Up With Chrome

TLDR: I need to be educated on browsers, what should I or should I not look for?

I’m decently tech-savvy but pretty new to the browsers discussion. I've always had the "if it’s not broken, don’t fix it" mentality about it. But now, something broke:

I’ve been using Chrome for ages on various OS (mostly Windows and Android at the moment) and I’ve always been pretty happy with it (I know, I’m new, I said).
Over time, I’ve started to lean more towards privacy and open-source values. So, I’ve been considering the idea of switching to something that might suit my needs better for quite some time.

On mobile especially, I’ve always felt the lack of proper customization, extension support, etc., particularly for ad-blocking. I’ve tried multiple browsers, including Firefox, Tor, DuckDuckGo Browser, Opera, Edge, Brave, and Samsung Internet (which surprisingly impressed me, btw). But in the end, I’ve always gone back to Chrome, because having everything in one place is incredibly useful, and 90% of the time I’m on desktop, where I’ve always had a good overall experience. This mostly thanks to the huge pool of extensions and add-ons available, and the compatibility benefits of being the market leader.

For me, personally, my browser is arguably the most important piece of software that I use, and by far the one I spend the most time on, both for personal and work stuff. I regularly spend over 30 hours a week on it, and it's highly personalized, tuned to meet my very specific needs using shortcuts/macros, themes, scripts, and dozens of extensions depending on which specific profile I’m using.

Chrome was perfect for this. But here’s the catch: Google phasing out Manifest v2 is a deal-breaker for me. From the start, I thought this was going to be crazy, too much backlash, and that it would never actually happen. The constant delays confirmed that idea. Then Google got serious about this, and by June, the support will be completely gone.

I’d need to find replacements for more than half of the extensions I use, and I figured if I’m going to spend that much time on this, I might as well migrate to a new platform that can support my work and my values long-term.

I’m looking for a balance between customizability, extension support, speed, and privacy, but above all, I want it to have solid long-term support. For this reason, I’m trying to stay away from microforks or projects that are available on only one OS or could vanish overnight if the developer loses interest. I’m willing to make some big compromises for the chance to have a solid platform with a large community behind it, but I’m very open to suggestions.

I’m really trying to get a feel for what’s out there right now. So, feel free to educate me on the topic and drop any tips, or general thoughts you think might be worth considering to fix/improve my browsing experience. Consider that almost my whole browsing has been on Chrome, so I'm using that as a reference.
I’m really looking to make a decision soon, so any insights are highly appreciated.

Edit: Trying firefox at the moment.