I would, in the case of an interstate purchase, have an FFL shipment component. I’d follow the rules.
I took your post to indicate the desire for a private sale with no FFL involvement (hence no 4473). Didn’t want you walking into a minefield, or have your post “misinterpreted” by unfriendly parties. Cool.
Another option is to build your own AR overtime by buying lower and upper receivers and other parts. The lower receiver has the serial number which would go through an FFL when you purchase it.
This request sounds like a set-up to get someone arrested.