Passkeys as a brand include both hardware-backed keys that can't be exported and are device-specific. These can be used for things like 2FA/MFA-type scenarios. They also involve a lot of site-specific keys that may not be hardware-backed and syncable. The neat fun thing is that they can be synced with hardware-backed keys for strong E2E between a user's enrolled devices and only the user's enrolled devices (plus maybe a hard to use recovery key). (That's basically how iCloud's Password/Passkey store and a lot of iCloud E2E in general seems to work.)
Passkeys in general, especially the focus on a lot of site-specific E2E shared ones, are very much "just like a password", but as the sibling comment points out, the switch to PKI alone is a huge security win and would stop a lot of the haveibeenpwned sorts of leaks and the overall attractiveness to crackers to break into various company's password databases, because only having a public key is a lot less useful than a salted/hashed password that might be broken or found in a rainbow table.
Passkeys in general, especially the focus on a lot of site-specific E2E shared ones, are very much "just like a password", but as the sibling comment points out, the switch to PKI alone is a huge security win and would stop a lot of the haveibeenpwned sorts of leaks and the overall attractiveness to crackers to break into various company's password databases, because only having a public key is a lot less useful than a salted/hashed password that might be broken or found in a rainbow table.