This is based on a post on Github (via Android Police) in which the message reads, “Support for the S9 and S9+ will be added in the next release, which should be released in the coming weeks.” There is no specific mention of dates so we guess Galaxy S9 and S9+ owners have no choice but to just wait.
In the meantime it seems that there are quite a few apps that are taking advantage of ARCore by updating their apps to support it. This includes IKEA who launched their Place app, an app that lets users place furniture in their home using augmented reality. Then there is also eBay who is using augmented reality technology to help eBay sellers figure out the best box size to ship their items in.
Even Google is getting in on the fun by launching their own fun little app called “Just A Line” that lets users “draw” in the air.