Obviously Zelenskyy was always going to reject the deal given it contains no security guarantees for Ukraine but that's just a starting point, I think it more outlines the US intentions above all else which are now transactional.
The US holds all of the cards because it and Russia can veto any UN security resolution and the US can veto any NATO action. I don't really know what Europe can do other than to keep Ukraine going in the meantime. Putting boots on the ground would be effective but that isn't going to happen given it means total war.
What I can see happening is that Russia will get the territory that it has taken and a ceasefire/DMZ will be implemented at the borders enforced by the US, effectively guaranteeing Ukraine's 'new' border in exchange for a cut of these rare materials. This is ripe to become similar to Korea where the parties are technically still at war but there is stalemate in the middle.
It doesn't actually even mean peace, it just means that Russia gets what it wants, the US gets what it wants and then Ukraine is left to rebuild which is perhaps where Europe steps in.