Brother has an S9+, (I have an s10+), and showed me he has chat enabled (IN THE SAMSUNG MESSAGES APP) similar to the release in Android messages (which I have been using but it doesnt sync with my gear s2). Has anyone else noticed or seen this? Googling it is impossible. Both phones are on the same carrier. This shouldn't appear on verizon but his phone can enable it and I only have the option to do so using the android messaging app from google. Really missing the stock when I'm on my watch and can't interact with my texts.
Chat messages in Samsung Messages is called "Advanced Messages". It doesn't work with Google's RCS implementation. Carriers have adopted it few years ago but you have to purchase device from the specific carrier. For example my T-Mobile s10e has it.
Is your device and his device unlocked or carrier devices?
Since you are on Verizon, the S9 & S9+ have RCS active. All of the other Samsung phones have not been activated on the Verizon network yet. You can search this on the Verizon website and confirm. They call it advanced messaging. I have been watching this for a while so I can have the ability to text groups and pictures via WiFi.
I know I can use Google Messages to do this now, but would have to get my wife and others to switch to that instead of Samsung Messages, Samsung Messages has some superior features that I utilize and can't get on Google Messages.