Definitely not. My understanding is they got significant market share on lunch - since it was during the pandemic chip shortage and they were the only ones with sub year lead times.
There's nothing in ISO 26262 that would prevent someone from using an RP2040 in a car. You'd just have to be redundant about everything which you have to do anyway regardless of the chip you choose.
Also, ISO 26262 is not a law. It's up to the auto manufacturer whether or not they'd require it and no single chip on its own can claim to be "certified" (or similar) for ISO 26262 since the focus is on redundancy and error checking (which means one chip would check the status of the other and vice versa, not some special internal consistency checking feature... That's just marketing).
Most "automotive" versions of chips (e.g. Atmel's stuff) are just branded that way. Atmel will make a claim like, "this chip has been tested to function properly under these sort of extreme conditions..." (that happen to match what car manufacturers are looking for) and then a car company would just trust that and make it so that only chips that are marked "automotive" and manufactured by Atmel will be allowed to be used by their electrical engineers (or suppliers).
It's all entirely arbitrary though: If you can convince the manufacturer that your board works fine under the conditions they require they'll probably buy it. Well, they won't hold it against you that you used one chip or the other. They just want some assurances.
There are several automotive standards for electronic components. GP was probably asking about e.g. AEC-Q100, AEC-Q101, and/or AEC-Q200. These establish that the device is going to work in automotive environments (temperature, humidity, vibration & shock) by verifying functionality while subjecting them to those conditions. A component may work without these tests, but you are merely hoping that that is the case if they haven't been tested. Hope is not a viable strategy for product design.
The AEC standards aren't enforced by anything and are mostly just promises that chip manufacturers make (the AEC itself is a private entity). Specifically, that any given chip will still be available in 15 years and that it'll operate fine within certain temperature ranges.
If some part claims to be AEC compliant it's basically just the manufacturer saying so. There's no independent body or even standardized tests to prove a part adheres to any given AEC document. Their own docs state as much:
AEC Certification
Note that there are no "certifications" for AEC-Q100 qualification and there
is no certification board run by AEC to qualify parts. Each supplier
performs their qualification to AEC standards, considers customer
requirements and submits the data to the user to verify compliance to Q100
In other words, it would be up to any given car manufacturer to verify the claims of any chip vendor using their own testing methods. Since they're going to have to do that anyway, slapping AEC-(whatever) on a product doesn't mean much.
If you test your part in similar conditions and make some availability promises you too can slap an AEC-Q100 label on to your chip!
