In general, Qubes OS-certified hardware does not guarantee full functionality across all components. Additionally, Qubes-certified computers may have known hardware-specific compatibility issues when running Qubes OS.
Could we establish a dedicated ‘Qubes-certified’ category alongside the Hardware Compatibility List (HCL)?
I agree. However, issues relating to product quality or technical support should be taken up with the sellers on their forums.
Except for Star Labs, since they do not have a forum, contact them directly instead:
So you suggest that if my Nitropad v56 having kernel issues/panic on the WIFI and/or GPU module using the latest Qubes OS kernel… I should talk to Nitrokey to get fixed? 
No, but if you are disappointed with the build quality or if something is obviously broken, etc. — such as bad keyboards, touchpads or squeaking screen hinges …
I wonder what you mean because that seems to say the opposite:
I ask for such forum category based on personal experience.
Nitrokey: I’ve encountered personal issues with their forum. They erase threads related to bug reports, help requests, and technical problems. In my case, I was redirected to their customer service where they blamed the Qubes OS project for what appeared to be a hardware issue. Any follow-up comments I posted regarding this on their forum were removed by moderators.
Novacustom: They edit users posts without leaving an “edited by moderator” notice.
Wow…
OTOH, last time I checked Star Labs didn’t have Ethernet ports (all USB).
It’s important point to security of QubesOS, since in such case you really need two or more separated sys-usb.
But we have no platform to talk about that.
Can you provide any evidence to support those claims?