About the other points.

I see your point, personally I prefer WebUsb, WebBluetooth and such to be completely missing, so it's much less likely that a bug allows access to these to a site.

Bluring camera background seems to me very specific to webcams, and even if chromium based browsers will do it for you, I think you are better off with running OBS and it's virtual webcam functionality, as it has been made for that purpose (video processing), and it can do much more if you want (including cropping, ways to improve video quality, or even do greenboxing). Introducing background bluring to the browser would mean more requests to add this or that effect (even if it should actually be the task of the web app), and I think it's hard to maintain even a single such effect (that does not blur everything, but only certain parts of the image) if your devs don't have extensive experience in video processing. This would be a feature that if introduced, either would break once and stay that way for quite some time, or would take significant development resources to find the problem and keep it working.