This is something that’s been brought up a lot in the past and the answer is no. The security team has evaluated the pros and cons on this and determined it’s not really viable. Passwords are saved locally on your device and even if they were to create a “password” to prevent it from being viewed from within the browser, it would still be easily accessible off of your device folders.
Passwords are encrypted on your device using your OS username/password. And, as you know, can’t be viewed in password manager unless they use your password/pin, which you shouldn’t be giving anybody.
All of that said, it’s not like Brave is saying no to it. They have had an open issue to it since 2020. You can see an official response on that at When Will There Be A Master Password? - #46 by fmarier
I also want you to realize that this has had a lot of topics over the years. I merged many of them together to a current open feature request over at When Will There Be A Master Password?