I see that OP is Canadian (at least based on his avatar)--not sure what features are available in Canada-spec Optimas but here in the U.S. I can get text message notifications on my vehicle (only) if I'm using Apple CarPlay (with my iPhone connected via USB--no wireless CarPlay in Optimas at this time). Dunno if something similar is available for Android (I don't own an Android phone so I never bothered to read up on how it can be integrated with UVO for hands-free stuff).
TBH I don't know if text message notification on the vehicle is possible if your phone is connected to UVO via Bluetooth; I'm gonna guess that it's not possible but someone could prove me wrong.
I have a 2019 Optima S I just purchased at the end of October and the only way I can get text messages is using the Apple CarPlay or Android Auto. I'm disappointed I can't get the text messages via the UVO interface. I contacted the Kia "expert" at the dealership and they also stated the only way to get text messages was vial the apps and not through bluetooth. Of course, he also stated there was no remote start on my car even though I have the ability to do it through the UVO app.