Read somewhere that it is relatively easy to adapt NetBSD's drivers into a custom kernel... maybe Serenity folks can go that way? Device drivers are huge obstacle for any fledgling OS.
One of Serenity's philosophical decisions is that as much as possible they build everything themselves from scratch. So even if NetBSD's drivers would be easy to adapt and have a compatible license they probably wouldn't go that route and would instead write their own drivers.
This is a noble and worthy goal in itself. Too much software development nowadays is just copying or gluing existing code. Clean-room implementations ensure we (collectively) still have the wits to rebuild and maintain the difficult parts.