Metroid Dread was a prototype 20 years ago and then was a dead project for most of those 20 years. The news was that the project was handed to Mercury Steam to be started fresh.

Switch 2 is expected somewhere between March and November of next year, and there are a lot of big companies in Spain, including Mercury Steam. Games generally take longer to make these days, so if the Switch 2 launches anytime next year, it would make sense for dev kits to be out already.

That's to say nothing of how much I trust the source, but there's no reason it couldn't be real.