Maybe browsers should looking at adding a "create account" API or something? Similar to "Login with Apple ID", but instead password managers could hook into it

Maybe browsers should looking at adding a "create account" API or something? Similar to "Login with Apple ID", but instead password managers could hook into it and create an account semi-automatically. This could also allow automation of "user+sitename@domain.com"-style rules. I know that creating an account isn't adding _much_ friction, but there is some and I could see myself appreciating this.