I just exported my iCloud password into a csv file on a MacBook, then imported that file into Firefox.

Agreed - I’m ready to bail on safari but don’t want to use chromium

The Keychain integration is done through a Chrome/Edge browser extension developed by Apple. Hopefully they will also port it to Firefox.

Apple has made an iCloud Bookmarks extension for Firefox which is still supported, so hopefully a Keychain extension will follow.

Most likely won’t happen as Apple doesn’t seem to care about Firefox nowadays. FaceTime on the web is not officially supported on Firefox and they regularly break iCloud on Gecko.