We haven't heard or seen anything about Pokemon Legends: Arceus since Nintendo revealed it earlier this year for the Switch and Switch Lite, and right now there's no word of when this will change. What we do have is a new and unofficial report about the game, which usually isn't worth putting much stock in, but this new report comes the way of a fairly reliable leaker when it comes to Pokemon news. That said, the new report doesn't reveal much, but it does hint at the release date of the game.
The report comes the way of Kelios, a prominent Nintendo and Pokemon insider, who notes that the footage used in the reveal of the game was from December 2020, which is to say, three months old and dated.
Adding to this, Kelios briefly touches upon the game's release date, noting that it's "pending," and that we won't hear about it until sometime later this year. Some have taken this to mean a delay is possible, which of course it is, but that doesn't seem to be what Kelios is getting at.
That said, as always, everything here should be taken with a grain of salt, especially as it comes through translation. I'm far from fluent in French and Google Translate isn't the most reliable means of translating either. In other words, it's important to remember, meaning and context may be lost in translation here.
Pokemon Legends: Arceus is set to release sometime in early 2022, via the Nintendo Switch, Nintendo Switch Lite, and possibly the Nintendo Switch Pro. Below, you can read more about the game, courtesy of an official blurb straight from Nintendo:
"Pokemon Legends: Arceus brings Trainers to the vast Sinnoh region as it existed in the past, long before the setting for Pokemon Diamond and Pokemon Pearl was established. Rich in nature and with Mount Coronet towering at its heart, this is a Sinnoh unlike anything Trainers have experienced before as they embark to create the region’s first Pokedex. As they start off on their adventure, Trainers will be able to choose either Rowlet, Cyndaquil, or Oshawott as their first partner Pokemon."