The Plain English Surface Duo update changelog(!)
(All About Windows Phone)

The original Surface Duo was perhaps closest to the original `courier`/Andromeda vision, in terms of hardware that folded back on itself 100%, but it was lacking in terms of some vital specs (notably NFC) and in terms of distribution and software support. Its Android 11 update, in particular, was MIA for a long time, but this has now been fixed and is available over the air. Here`s a summarised, plain English changelog, if you`re interested. Though note that a software update alone isn`t enough to bring the original Duo close to what the newer Duo 2 is capable of.