Building Kernel App for fast GPIO

[nimblemotors]

Hello, I am quite interested in the Pine 64+ with the Gigabit ethernet.
For my project, I don't really need an OS, I'd be happy with a fast $20 Arduino with Gigabit ethernet,
but there is no such thing.  I also need fast bootup, so don't really want an OS layer.

It looks like what I need to do is build a kernel and boot it from the flash drive,
and have it run my application.  I need really fast access to the GPIO pins for some gigabit speed communication to devices.

Any help here appreciated, or if you can suggest other $20  gigabit speed hardware.

Thanks!
Jack