I'm hoping we can put it into the SDK 27 release.
This is a super popular request. We only haven't done it so far because (a) you can do a lot of the things people want to do with Firebase with just JS, esp. now that blob support will be available soon, and (b) there is some complexity with integrating it into Expo, and (c) push notifications just won't work with the Expo model since we can't give out the APNS tokens for the Expo client app to everyone, for example.
But I think it still makes sense to do it so we'll do it soon (unless there are unforeseen complications which there often are with software!! And no promises on date, etc. Just telling you what I'm hoping for.)