It's getting a bit crowed in the EV market-space and some EV makers like Rivian need to do more than their competitors otherwise they will end up being yet another EV maker, which now is not enough.
The Amazon fleet partnership is very positive and several other deals in Europe too. However, Rivian just needs other ways to utilise its technology just like what NIO is currently doing in China.
If Rivian follows that path and avoids being just a generic EV maker, then its stock is a straight buy in my books but I would hold for now and see what the competitors (especially Lucid Motors) are also doing first in October.