Updated: solved thanks to the info at this message
I've been messing around with this laptop (Thinkpad E495) and FreeBSD since last year. While using the 13.0-CURRENT version until march, I was able to change the screen brightness via:
$ doas sysctl...
This is not about X. In general. For example, how to get console on LCD?
When running the official FreeBSD 12.0 for BeagleBone I see:
% grep fb0 /var/run/dmesg.boot
fb0: <AM335x LCD controller> mem 0x4830e000-0x4830efff irq 43 on simplebus0
But there is no such device node. Am I missing something?