We're working on it! We've started with some of our components and intend to open more in the future.
The idea that "open-source = trustworthy" only goes so far. For example, the same tech company that offers a popular open-source browser also has the largest ad/tracking network in history, with that browser playing a significant role in it. Another company with a closed-source browser (using WebKit like Orion) is on the forefront of privacy awareness and technologies in its products.
When it comes to things like browsers, due to the sheer complexity and difficulty to truly audit chromium, I don't really consider chromium to be "open source" in the same sense as many other apps. Legally, you can see and edit the code. But in practice, it's impossible to audit all of it, and the development is controlled by a single corporation who puts secrets in it, or removes features that harm their interests (manifest v3). Personally, I consider Minecraft Java to be closer to open source than chromium is.
To say that:
The idea that "open-source = trustworthy" only goes so far
is really just a cop-out and excuse for not being transparent with their code and what they are doing.
If its not open source 1) you can't fully trust/audit. and 2) you'll be left in the dust should the company cease to exist as nobody can continue development.
If Firefox is not private enough use Librewolf. If you're interested in something new and exciting give Zen Browser or Floorp (both based on Firefox) a spin.
I know it's a privacy focused browser, and I've used it on my iPad. It's a decent enough browser. The best feature is that on iOS it actually supports plugins like ublock.