I think that one of the reasons they (frontier companies and the gov) will be putting so much effort into curtailing bugs and vulnerabilities is to limit the blast radius of future AI models. Imagine with the new Sol Ultrafast, they could have pwned Hugging Face in 6 hours and not 4 days (IIRC).
It also seems likely to me that the US Gov. probably already has routine mechanisms for compelling targeted software updates for persons of interest, so I'm not sure that a more formalized backdoor than automatic updates is going to be surfaced in the mainstream, unless that is avenue is also cut down somehow.
Google has started publishing "binary transparency", this would help detect unusual software updates, while other methods (including AI) would help detect normal backdoors.
Basically in the AI age, the difference between a vulnerability and a backdoor diminishes..
I may be naive, but how would binary transparency be effective if they ship an update to disable that on a target device? As long as there is a need for legitimate automatic software updates, the possibility of pwn updates will always exist. Plus a myriad of layers, keys and other stuff they could use NSOs to 'seize' and inhibit knowledge of their effort from leaking, or cleverly hide in plain sight. And someday, with the help and speed of AI.