Thank you! Mostly, because Chromium based are used by the most people around the world, and it's related to my job in web-dev and security, since at least 2014.
It's hard to guess what you actually meant, but let's guess...

1. For a client, do you mean Firefox/LibreWolf/non-vendor?
   Has less features for modern web-dev. Well, sure, yet the development environment is much more featureful in Chromium.
2. For a search engine, do you mean a SearXNG instance or such as services as Kagi?
   Of course, but it's unstable/erroneous from my experience, at this point of life. Yet, is monitored for better times.