Based on everything we learned about coreboot, we think you can port a laptop board in 40 hours or less. There are tools that you can use to dump most of the code you need. For instance, the GPIO can be done in 30 minutes, as opposed to the 30-50 hours that was quoted by several developers.
OK, so why didn’t you just port it yourself in 40 hours? Apparently it’s super easy.
On grapheneos it’s a setting, 18 hours by default I believe, but adjustable from 10 minutes to 72 hours.