All software products have an End Of Life date. This is also true of all Operating Systems. They reach a point where there is no longer support for bug fixes or security updates. When this happens you should migrate to a supported version.

No one in the channel is going to buy any claimed ability to 'secure' your OS and while we may be sympathetic to difficult choices such as 'tied to industrial equipment' you find a support contract.

We cannot help you with finding media, etc because EoL does not mean the Operating System or Software is out of copyright. Consult the copyright owner or a lawyer for clarity, it's not something to debate in channel.