I'm sorry to hear you couldn't run it! What are your specs if you don't mind me asking? We avoided using nanite as much as possible since that tends to be a deal breaker on older GPUs, the grass is unfortunately the single instance of nanite we're using though.
We're also using lumen for GI/reflections as well since that's just the default nowadays, but we may try using static lighting instead and disable nanite altogether just to see if we can get it to run well on the Steam Deck.