I used JSON-LD spec because it is preferred by Google, but it requires a lot of duplicate effort of the actual page content. Its almost as if it is designed for sites that use heavy JavaScript frameworks and not for HTML/CSS sites.
Usually the dynamic data would be generated by the server. eg. if you have an eCommerce site, it might update prices, stock remaining, applicable regions, etc. That would then be pulled into Google Shopping or whatever other service might consume it.
