Yes, a spectacular failure resulting in Sony giving up the handheld gaming market entirely to Nintendo.Vita was a failure.
What you don't understand is that Steam Deck is even more of faliure than vita
And no the Deck isn't a failure... Valve have already confirmed future Steam Decks, and the market is flooding with others who want to get in on the handheld PC market.
Vita failed to create a market to sustain it, and developers gave no shits about it.
Deck doesn't have that problem.. the market is there.. and growing, and doesn't rely on developers supporting it.