I'm like why is my browser asking to store them? What if I'm using another browser? Why is my password manager fighting with my browser on where to store this passkey?

The answer to all of these questions is “For the exact same reason they do all these same things with passwords”

Think of a passkey as a very, very complex password that is stored on your device (or in a password manager) that you can use to log into websites with without ever having to know what the password is, and it’s never stored on the site you’re logging into, even in a hashed format, so it literally can’t be exposed in a breach.

It’s the exact same technology you use to connect securely to every website you visit, except used in reverse.