Clearly not. A reasonable expectation might be though that if you want to sell your multi million pound products to a captive public sector, you have to publish all the source code and the means to build the binaries.

Open source means just that - it doesn’t imply one sort of distribution mechanism over others.

Yes. Once it's signed by somebody accredited to review it for safe train use.

The same way technical diagrams for roads, bridges and other public infrastructure are public.

In most OECD countries food needs to be labelled with a full list of ingredients.

Your GP can read scientific papers about the efficacy and risks of a new treatment.

(Yes, many papers are paywalled but that's irrelevant compared to secrecy)