Currently, the apps share URLs by adding a query to the URL:
?source=app
?source=app should be changed to the following:
iOS: ?wprov=sfii1 for image cards, ?wprov=sfti1 for text shares
Android: ?wprov=sfia1 for image cards, ?wprov=sfta1 for text shares
In iOS, WMFShareOptionsViewController (init, respondToTapForCardGesture, and respondToTapForTextGesture) should be updated accordingly.
In Android, ShareHandler.java should be updated.
Additionally, a VCL patch should be submitted in the fashion of https://gerrit.wikimedia.org/r/#/c/120617/, but generalized for handling this wprov parameter with an alphanumeric value.