Is Facer coming to Garmin soon? Facer support said they've added it to their list but is there a reason it hasn't happened yet considering Garmin IQ is quite open source?

There is nothing stopping them. My guess is that they don't like the idea that they must use Connect IQ to publish the watchfaces and there is no good payment system in Connect IQ so they would have to implement that in some way.

It will also be hard to handle the creators (individual watchface developers) in Connect IQ since the publish process is a bit clunky and from what I can see not possible to automate.

I don't really see the benefit of Facer for Garmin since it is so easy to create and publish your own watchfaces. Why create your own watchface and then let someone else upload it to Connect IQ?

You can also use the Watch Face Builder | Garmin Connect IQ instead of Facer