It is better to switch to Firefox. But chromium forks can generally do whatever they want, it's just a matter of maintenance burden. e.g. nothing is stopping a Chromium fork like Brave from running a manifest v2 compatible appstore, but it'll cost money to make, maintain, and operate, plus you have less discoverability as an app developer when using a smaller app store.

Can we be certain this isn't in the obsfucated binary blobs provided by Google? How can people act like Chromium and Chrome based browsers are free from Google BS when most of them still use precompiled hunks of executable provided by Google that we can't see into?