What does this game classify as? And why do you think so?

A sequel ?

Just from looking at the trailer, there’s enough addition to confirm it’s a new game and not just a remake.

They went with New Pokémon Snap, like with the new 3DS which was a small improvement and not a completely new thing. If it is a full sequel why not Pokémon Snap 2 ?

New Super Mario Bros. was a new game and not a remake of the NES original.

New Super Mario Bros was a new 2D Mario game. Based on what we have seen, this is a "New" Pokemon Snap game and therefore a sequel. Why they did not call it Pokemon Snap 2...?...I have no idea. It makes little sense to me, but this is not something Nintendo has not done before.

Oh boy... not this again...

We only have one minute or so of footage, but. Everything points to this being a new game.

In that minute or so footage, we see all new areas and Pokemon from even Sword/Shield.  The only thing that it could be other than a sequel is a straight up reboot, which would still make it a whole new game.  And since a general timeline for Pokemon Snap would be completely unnecessary, I cannot fathom why they would do that.

It's possible... Although HIGHLY UNLIKELY that it would be something like the original game remade plus a few new areas.  I'm like 99.9% sure it's an entirely new game, but it could just be a very misleading trailer.

It's a brand new game just like "New" Super Mario Bros.

Totally new game with new setting, new Pokemon, new everything. Why is this even a question? This is certainly more of a new game than Miles Morales is.