Those phones have already been on HyperOS 3.0-3.1 for quite a long time now (with Android 16). Literally most modern Xiaomi phones already have HyperOS 3 (Xiaomi 13T being a weird exception that should be corrected in the coming months, once they solve the issues found on the Indonesia build that required an update to the Linux kernel for Android 16 to work).
Now these few phones (17 series + 15T) are getting HyperOS 3.3, with Android 17. That's the news: the ".3" part of it that gives them Android 17.
The rest of the phones won't get HyperOS 3.3, they will have to wait for HyperOS 4 to be able to get Android 17 (probably starting in September, and general availability around October-December).
I guess AI wrote the article, as it makes no sense that it completely misses the main subject of these recent updates.
Xiaomi is currently rolling out a new update to several smartphones, bringing the Xiaomi 17 series and the Xiaomi 15T Pro to HyperOS 3. The new operating system is based on Android 17.