Sykar
Arcane
I dunno man, Metroid Prime sticks pretty close to the core and checks all the boxes for me despite the fact that one could technically put it in the first person shooter box and call it a day...I think the hard line is that Metroidvania should be a platformer.also think it's tough to draw hard lines between when something is like Metroid, Zelda or Dark Souls as there are many commonalities of the core gameplay/exploration aspects, and certain games
Metroid Prime is a great Metroid game, and a great game in general, but it is not a Metroidvania. This is also not a bad thing. Categorization is just that, categorization. A game does not become good or bad just because it does not belong to a certain genre.
The reason why Metroidvania games have such a narrow definition tied to 2D platformers is the fact that this kind of open exploration they offered was a novelty back in the day while exploration was there in 3D games early on.