I also happen to need this.
My current password management setting involves 3 KeePass databases. (a personnal one, and two other for companies I work with).
In KeeWeb (my KeePass client), I can quickly switch from one database to another:
I’m currently deploying two separate Bitwarden servers (a personal one, and one for my company), and I’d like to have a similar behaviour. Unfortunately, it’s not possible, I have to logout, change the server URL in the client settings and relogin, which is really tedious.
I really don’t care about unified search or linking accounts together, I’d rather have a simple way to quickly switch from an account to another. Something like a configurable list of identifies, to add a bitwarden URL and user email, and a dropdown on the login form to pick the one you want to use before filling in your master password. Since it’s purely a client side change, I believe it could also be simpler to implement (but I may be wrong).