Seriously though, pick up a Pixel 6, flash it at home via Web-USB.
My only qualm is that the Google bootloader doesn't show a QR code on boot to verify the kernel image being loaded, instead it simply shows a big yellow warning saying the OS is unsupported with no way of verifying if it's the GrapheneOS image you loaded or one the maid loaded while you were AFK.
I have hated android not meeting my own personal watermark in respecting open dev and privacy forward user design at its core. This project, although not core and on the fringe, gives me a small glimmer of hope in a dark smart phone world! Been a stable daily driver for like six months now.
Once upon a time it at least showed part of a hash or somesuch ostensibly uniquely identifying the OS, such that it would change if an Evil Maid flashed a new one.
I honestly don't know why we can't have a system to visualise the signed image source as the default. Put any public key you want in the firmware, show a 32-64 bit fingerprint of the loaded key as an abstract pattern and only boot an image signed with that key. Manufacturer doesn't get any special treatment.
Fairphone at least shows a hash on boot as well as the scary yellow text when relocked. Calyx is available, don't know about graphene.
Many people have tried to pay me to make them a custom ROM based on GrapheneOS but with their name and reskinning notepads and encrypted chat apps. They'll claim it's for privacy-focused businesses of course.
You do have options:
1. Do you want to buy a third-party device like a NitroPhone? If you can afford to purchase a phone in the first place, then purchase a used phone to try flashing GrapehenOS. You can buy multiple used devices for the cost of such a device, and then you can familiarize yourself with the flashing procedure.
2. Have a friend help you. There are probably events in your town that you could find on Facebook, Reddit, or Meetup (e.g., OS install parties are a thing).
3. Wait for the official project to begin selling their hardware: https://twitter.com/grapheneos/status/1490518600339308544