Helper apps from ePub

Hi, I am working on an ePub field guide for naturalists. I did not find a way to include a manifest resource intended for a third party app. Part of me understands why that would be a BAD idea (malware) but here is my use case.

The field guide includes various nature trails. I can use a Google Maps hyperlink but I would like to include a standard GPX file for people like me who are extremely paranoid about trackers (with good reason, just found out that ICE recently bought geolocation data from weather apps to learn the locations of undocumented immigrants and arrest them, trackers are killing the usefulness of the Internet). Anyway, I would like to include GPX files that when clicked, allows the user to import them into whatever app they have on phone/tablet/desktop for handling GPX files. Obviously this won't work with dedicated ePub viewers, but it could work on platforms where the ePub viewer is just one of many applications.

I could host the files on the Internet and link to them within the ePub but that is more fragile, servers could go away or the user may not have an Internet connection, etc.

Does ePub not have this ability? Can it be added to a future version?
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Sent from my Android device with K-9 Mail. Please excuse my brevity.