ChromeOS lets you run Android apps which integrate nicely enough (eg opening links in the app), and also there's the virtual Debian (by default) part that doesn't integrate as well but is more flexible. So yes, you can run other browsers although last I checked it was a little bumpy.

Last I checked Brave had no support for large screens (tablets, foldables, chromebooks) on Android at all - it was horrible from usability perspective.

On later chromebooks you can run Linux apps and android apps.

If you need to test in a lot of browsers it's not a terrible idea as you can run both desktop and module browsers.