In my opinion, the web browser is the single most important application that should be sandboxed on a system. We use them to access nearly everything on the Internet, including resources that are routinely laden with obfuscated JavaScript.
Every attempt should be made to separate the browser from the host system, and circumventing that safeguard in order to facilitate direct access to your password database is risky at best.
Edit: I don’t mean to suggest that I have the perfect solution either, but I keep everything sandboxed and just opt for KeePassXC’s native global hotkey for auto-filling credentials.