I'm using a router distribution -- no names please -- where the firmware build process is so intricate that their documented way to build LTS .iso images is via a docker based system. I've had very little luck (until recently) in getting that to actually work.
They provide nightly .iso images, but charge an arm-and-a-leg for the LTS images.
I've tried to use their nightlies, but they were subject to considerable churn in the last few months. That resulted in broken firewalls/routers.
I will NOT trust my firewalls to that, sorry.
In their defense, they _do_ have a way for "community members" (i.e. folks unwilling to pay $1000s/year for a stable build) to gain access to the LTS images. However the bar they have set to gain access is so high that my filing a bug they graded as "high priority" and then tracking down and verifying the workaround for a release candidate didn't qualify me to access the images.
I agree there is a gray area, and that the core developers deserve to be paid. I am actually willing to pay them for their software, but not $1000s/year.
In my honest opinion, they have crossed a line.
(Edited: changed "fix" to "workaround" above.)