Post 1. suggests disconnecting the display. That's not an option for me. It also mentions a package named 'vbetool' and that 'vbetool dpms off' may do the trick. Although there's no available openwrt package and therefore untested.
Post 2. suggests using 'setterm' to turn off the display. I was able to test it and it works but it only blanks the display but leaves the backlight on.
setterm -term linux -blank 1 > /dev/console
I was wondering if someone successfully implemented a software solution that turns off the backlight.
--blank[=0-60|force|poke]
The force argument keeps the screen blank even if a key is pressed.
I forgot to mention that I also tried the following which made no difference.
setterm -term linux -powerdown 1 > /dev/console
'acpid' is available as an openwrt package. I read up on it at the link that you provided. It's possible to use it by sending an acpi event, but it does depend on 'xset' or 'vbetool' to turn the backlight off, rather than adjusting the brightness.
I did find two openwrt packages: ' kmod-backlight-pwm' and 'kmod'backlight'. Although, I couldn't find any details how they could be utilized in my use case scenario.
Thanks for your suggestions!