I think the notion of the Dyad is pretty guff. I’d rather that Rey’s and Kylo’s bond was emotional, slightly aided by Snoke force-connecting them. It just feels pretty nonsense to have a new bit of force lore introduced in this one which seems to be 'you’re powerful and Palpatine can eat you.

I’d rather that the new force-thing which happens in this movie is simply that Palpatine can rip the force from force users. It makes him way more monstrous, just like the original lightning did in ROTJ.

Rey is a naturally powerful and well-honed (if not long-trained) Jedi, with a little dark leaning, a close relationship with another powerful force user, and near the end, the support of a bunch of ghosts. That’s good enough for me to justify her power, I don’t think we need a whole other thing, especially one so clumsy as the Dyad.