On the mobile site and iOS/android app, I'm unable to find how to view featured questions for particular tags. I can see the choice for Active, Newest, Votes etc, but Featured isn't in the list. Would it be possible to add this feature?
I'm not sure when it was added, but the iOS app does have a feature for filtering by questions with bounties.
On the Questions page, you can change the sort by tapping the search type on the top left. Next tap the Filter option and select With Bounty.