Preventing POD data from being copied

This seems to me a major point, since it is not technically feasible to prevent apps from harvesting and reusing user data, similarly to how they do it now.

Similarly to how rights to digital media are hard to enforce, rights on personal data are also hard to guarantee. Since they can be copied and moved without affecting the source.

Requiring some legal “promises” from apps, which is a form of licensing out own data, seems necessary, and I’d guess will emerge.
I strongly suspect there are more discussions about this.
One, with great points about connections to GDPR is here:

Indeed, looks like Solid provides technical basis to support GDPR (and similar policies).
But as far as I saw, there is not an established framework to implement this link.

Or is there? I am quite new to this. Are useful developed guidelines how to “license” (restrict use, by time and purpose) of data which is allowed to be read from the pod?

Does anyone know of relevant standards, documents?

I should say that I tried to some of my own apps, and solid makes it so much easier, conceptually, to handle user data, by never storing it at the app itself. Maybe not all developers are used to this approach, but I really hope it is widely adopted.