"Jupiter" is the Valve reference for SteamOS itself. Nothing to do with the hardware.
The original Steam Deck is Valve Jupiter, running on Neptune (OG deck hardware) which was Aerith (the APU). The Steam Deck OLED is also Jupiter, but running on an updated Neptune with the Sephiroth APU.
Deckard is the VR headset standalone-ish project. Roy are the next-gen VR/Index controllers. Ibex is the standalone Steam Controller 2, which will likely launch near/with Fremont is the set-top Steam Machine.
New info from a reliable source suggests Valve's SteamOS release is imminent. Code changes hint towards expanded hardware support, which aligns with official reports that SteamOS will soon be available beyond the Steam Deck.