Now, this could be a controversial one, because of the added ambiguity.

There is no way to indicate that an entry has been sampled because of the very definition of sampling. But what can be done is a boolean field added to the n-th (where n = first) and every subsequent entry within one tick. Let's call it sampling_threshold_reached for the lack of better name.

This could be helpf

The rule would raise info alerts for each script it found along with the integrety hash, as per
https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity

This could just work on URLs that are in scope - it would just be useful when you're trying to create a CSP for a specific site.