The device doesn't meet the project's requirements. Also, it's not about GrapheneOS requirements being exceptionally high. The team has said that they'd even be willing to support a device that doesn't have all of the features that current generation Pixels do, but there are some things that we cannot afford to budge or compromise on.
In reality, it's more the fact that Pixels are currently pretty much the only device doing the bare minimum while allowing all of that to be used with an alternative OS.
/e/ in particular is known to produce extremely insecure offerings. Please take a look at an incomplete collection of details regarding /e/ from the developer of DivestOS - https://divestos.org/misc/e.txt
It's not a project we can recommend or endorse in the first place, on top of the hardware they're crowdfunding not even being close to up to par for GrapheneOS support.