The PSP-like handheld will ship with official SteamOS support "provided by Valve Corporation"

Update: Or maybe it won't, as Valve is now saying they are in fact not working with GPD.

GPD has announced that the 2025 version of their PSP-lookalike, the GPD Win 4, will ship with SteamOS, with “system adaptation provided by Valve.” This makes GPD the latest manufacturer to confirm official SteamOS support, signaling that Valve is gearing up for a broader public launch of SteamOS on other devices. However, it’s still unclear whether SteamOS will be available only to OEMs or if we’ll be able to install it on our own PCs at home.