Re: My take?
There seems to be a general rule of thumb that when US intelligence departments leak alarming stories via compliant press contacts, it's usually the case that the US is already doing this themselves and are sweating buckets over the thought that someone else might be doing it as well. We saw exactly this in the run-up to the Stuxnet reveal, and we saw exactly this in the backdoors being installed in Cisco networking equipment.
I remember the same sort of vague but alarming stories claiming that foreign powers were infiltrating SCADA systems and could use that do destroy utility equipment. They even built a lab type setup of a diesel generator with attacked SCADA system and demonstrated it. Meanwhile the utility industry scratched their heads in puzzlement, because despite the alarm and panic in government, industry couldn't pry any actual details out of them so they could take preventive action and nobody was seeing it in the wild. And then the Stuxnet story came out and we found out the panic was about how the US (with the assistance of Israel) had infiltrated the SCADA systems controlling Iranian enrichment equipment and was using it to conduct sabotage and the US were afraid they would be hacked back.
To go back to the mysterious motherboard chips, if this was real, I would expect someone to present actual hacked hardware along with demonstrations of what it did. After all, if the story were real then it's not like Chinese wouldn't already know everything about it, so what's the point of hiding it?
And Amazon's and especially Apple's denials are pretty strong. If they were obfuscating the issue, then they would just release their usual vague waffle.
I suspect this story is complete bullshit. The use of a security company in Ontario Canada is also very interesting. At this very moment the US is putting lots of pressure on Canada to try to get them to ban Huawei equipment from important Canadian networks. It would not be surprising if this whole story were to be an exercise intended to pressure allies into stepping into line behind the US in freezing Chinese tech companies out of western markets in favour of equipment that has the backdoors of "friendly" countries in it.