Google uploaded some of its apps in the Samsung Galaxy Store
Looking at this reciprocally, Samsung’s own software has been available in the Google Play Store for quite some time now including apps like Samsung Health, SmartThings, Galaxy Wearable and more. This makes sense, as Samsung wants consumers outside their ecosystem to still be able to use the company's wearables with phones from other brands.
One possible explanation of why Google apps appeared in the Galaxy Store may lay in the screenshots of the aforementioned apps - WearOS’ in particular. The interface in the images seems to be in Chinese, suggesting that Google is trying to reach Chinese consumers.
On the other hand, WearOS and Google Translate won’t work at all without Google Play Services installed on the device, and the latter is still inaccessible from China. It all might seem like a futile exercise but the only other explanation is that Google wants its software to be more easily available/accessible on Samsung phones - If people prefer to use the Galaxy Store more often, they’ll now find some Google stuff there too.
We might have to wait a little longer before the reasoning behind all this becomes clearer, but there’s no harm in Google apps showing in as many places as possible.