Sure but I would like to see something more integrated. Browsers are a good example actually, allowing extensions to add all kind of "missing" functionality on websites. We don't have that on mobile or desktop apps and would have been nice. It's one of the strengths of browser based apps.
No one would actually do this though. You could do this with a browser just fine with an extension but no one is going to spend their time adding advanced features to someone elses paid product. It would also risk breaking on every change.
I know I wouldn't build something like this, but many people do, there are many Strava browser extensions out there. I used VeloViewer for many years before I dumped Strava altogether.