This will involve some dispatch process. Something similar to T194950: Include Wikibase dispatch lag in API "maxlag" enforcing should be done, but also notice T238796: Entity and non-entity edits should use different maxlag.
I have created a prototype of how SDC could be used on other wikis (as promised "coming soon" in the original vision of COM:SDC) to auto-generate image captions and citations. You can see examples in the "tests" section here: https://commons.wikimedia.org/wiki/User:Dominic/SDC_citation_tests
Right now, this can only be a proof of concept, since the very first step will be even allowing access to SDC in the first place from other wikis who would like to use it.
As part of my WMF project grant, I shared this work in a recent public meeting, and asked folks who are interested in seeing this work done to comment here asking it to be prioritized! Here is a link to my presentation with more info: https://docs.google.com/presentation/d/1GzMcBRxJe-8NwZfIHnCYW8cMmUYh3zd2d_psaUh2h6Q/edit?usp=sharing
I'm trying to improve the SD of my institutional uploads (I'm not a member of DPLA, but like the idea of improving/standardizing data). I'm envisioning that creating more detailed/standardized captions (which link to the institutions) will increase access by them linking to either a category in Commons or a Wikipedia article. I would have to look more into how it would be done, but that link could either go directly to a category in Commons for institutional uploads or to a Wikipedia article with a [Template:Commons Category] or something similar. I have a category in Commons of uploads from NAL's holdings, for example. I also have some of the uploads further categorized into their specific collection (Ex. Farmer Bulletins, NAL History) Visibility is key to access and I think linking users directly to the institution and their other items will encourage discovery. Hopefully I've been clear.. this is just what I've been thinking about since learning about it. Please let me know if I can clarify anything!