Yeah, reading through the linked https://hub.libre.computer/t/source-code-git-repository-for-... really sours my opinion of Libre Computer - shipping with UEFI so you can just use generic images is a huge advantage, but creating your default images (and firmware! which is worse, IMO) with a proprietary process is such a big red flag that it makes me question the whole thing. If the firmware is FOSS and you can build it yourself using only FOSS inputs (which isn't obvious to me from that discussion), then you could do that and any old image (again, UEFI to support generic images is a huge win) and it would be fine, but the fact that that's not the default really makes me question the values/culture of the company.
"The distribution builder is a proprietary commercial offering as it involves a lot of customer IP and integrations so it cannot be public."
Seems like a supply side injector to me!