Hello. In my opinion, it solves most of the issues, but to be fair, the stock camera app also got much better over the last updates. You don’t have to root the phone to use gcam. You just need to enable installation of apps from unknown sources. (It should prompt you when you try to install the apk file.)
Is it likely fairphone will publish camera-api2 updates soon to allow 48M and ultra wide lens access?
Yes, but we currently have no idea how long it’ll take. (Note that the issue has been reported for more than 7 months.)