One notable exception is the PC Engines APU 2, though that’s stretching the definition of modern.
Seriously: Pick a laptop SKU that is still being manufactured and has similar ergonomics to a MacBook Pro or classic thinkpad (centered keyboard + trackpad, 4K screen, all the other bits in the right spots, reasonably quiet, 8 hour real world battery), and mark it up by $200. Sell it from a site that OpenBSD links to.
Make sure the manufacturer agrees to build that exact laptop for at least 5 years. (Moore’s law is dead, after all.)
Have the project test 100% of the hardware devices in that laptop on each point release, and donate the $200 markup to the project.