Right, I looked at the web page and saw they offered a Pixel 8 Pro with 1tb of storage. As far as I can tell, Google only offers up to 512gb on the Pixel 8 Pro. I would just buy a Pixel and install GrapheneOS.
Discussion
No convenience outweighs the risk in these cases.
To anyone considering this: Just take a couple hours, make it a weekend project if you have to, it's fun anyway - Follow the GrapheneOS tutorial, verify your GrapheneOS ROM's hash, and install it the proper way. You'll feel accomplished, it'll be yours, and you'll know no one messed with it. No trusting, just verifying.