Yes, the Pixel has specific hardware and security which makes it ideal for a private/secure phone. So it is unfortunate that a purchase supports Google, however the pixels are cheap so I assume Google is taking a profit loss to gain market (and data).
Graphene does have a web installer, so rather than the old days of connecting to a command shell and typing cryptic commands( for the average user) you connect your phone and click the web install buttons in order till you reach bottom of webpage. it gives you an instruction how to boot the phone into certain modes with volume and power buttons. While my mom isn’t going to work with this a 9-10 year old could do it.
/e/ OS was selling preinstalled phones, I haven’t seen the same from GrapheneOS yet…but I have not checked in depth to see if somebody is offering this.