The Galaxy S23 might be Samsung's first smartphone lineup to ship with Seamless Updates support out of the box, not because of a change of heart from the Korean Tech giant but because Google will reportedly mandate virtual A/B partition support from smartphone manufacturers with the release of Android 13.
Seamless Updates is a feature that Google implemented in Android 7.0 Nougat. It allows a device to download and install new system updates to a separate partition in the background and requires only a simple restart for new updates to be applied.
Although the software giant initially wanted to push OEMs to adopt the A/B partition for Seamless Updates with the launch of Android 11, it eventually loosened its requirements due to internal storage concerns. Samsung is one of the manufacturers that have yet to adopt Seamless Updates, but this could change soon.
Google to make Seamless Updates mandatory for Android 13 devices
Google managed to lower storage requirements for Seamless Updates through the implementation of a virtual A/B partition. And as discovered by @MishaalRahman (via Esper), Google will require smartphones running Android 13 to adopt this virtual A/B partition. The virtual A/B solution requires less storage than the first A/B partition implementation.
In short, this should mean that Samsung's next flagship phone and future models running Android 13 will offer Seamless Updates, which will allow customers to download new system updates in the background without having to render their phones unusable for a few good minutes throughout the setup process.
Since the Galaxy S23 is expected to be the first Samsung phone to ship with Android 13 out of the box, it should offer Seamless Updates from day one. The feature is not supported by the Galaxy Z Fold 4 running Android 12L, as seen in the screenshot below, but this will probably change in the future once Android 13 rolls out.