Those checks are then performed on the MITM device. Instead of an error page the device could return the same sort of page that your browser would otherwise display for you. The connection has been MITM'd after all.
Yes you can. Do what corporate firewalls do. MITM all TLS connections with your own personal CA. Don't allow any traffic streams that you can't MITM to leave your network.
Something resembling this has actually been observed in a species of deep sea snails. Iron sulfide is incorporated into the hard bits (shell, foot armor). (https://en.wikipedia.org/wiki/Scaly-foot_gastropod)
In the short term? Perhaps. They might just develop their own proprietary OS - they already design custom CPUs!
I imagine it would depend heavily on how large the liability was. I expect individual components would begin being replaced with "certified" commercial alternatives. If not existing ones, definitely new ones. Remember that they make money by selling to customers who would also be subject to the same rules. Look at healthcare, aviation, and finance for concrete examples of the effects (both negative and positive) that red tape has on software and IT policies.
There's an entire FOSS ecosystem and the vast majority of it is composed of small-ish slow moving projects. The tech industry is also an entire ecosystem full of small and medium sized players. Even if behemoths such as mainline Linux and AWS somehow survived unchanged I would expect a much greater chilling effect on smaller players that couldn't afford to take on such risks. New companies and software projects would become very difficult to get off the ground (healthcare is a good example here). With few to no new entrants forward progress would slow to an absolute crawl.
All of this has downstream effects. Fewer consumer devices running Linux would mean even less hardware support. Security related liabilities would almost certainly mean more vendor locked hardware. Would companies like Purism remain viable (or even legal)? The steady stream of new FOSS users and contributors would almost certainly dwindle.
Depending on how such regulation was written, could open source contributors themselves become liable for a freely provided product?
That is due to issues with how Equifax operated (and related lack of meaningful consequences). It has nothing to do with a lack of liability for software companies.
Local development would rendered unable to compete with the fast moving zero-liability model that quickly and cheaply delivered the features that consumers wanted. Either it's import would be banned or the local industry would crumble.
The point is that if legislation were introduced that resulted in liability it would likely completely decapitate the FOSS ecosystem (among other things).
Typically the LLM queries external tools as appropriate and then incorporates the result into the response.