Ubuntu 18.04 issues
First of all I'm completely aware that 18.04 is currently not supported OS.
However we are using the 18.04 mostly without any problems, the main issue we are seeing is that after we install the upboard-extras package from the 16.04 repo the system shutdown sequence seems to wait for some kind of IRQ that is never received and times out in about 3 minutes. This results in 3+ minutes shutdown/reboot sequences. Everything else we managed to run without any issues.
Please consider this issue when you are preparing to officially support 18.04, or share with us any knowledge that could help us mitigate it even now if you know how