Hi @Bia and @ZachMonroe - looks like we forgot to add target mode to the web app. At the moment, we have a few inconsistencies, for example - you can't create a head-to-head challenge on mobile. Creating target mode was kind of compensating for the lack of head-to-head (we get a ton of support request for head-to-head and think that doing them on mobile would cause even more support, so for now, it's a web only feature).
I'll talk to the team about adding target mode on the web in the next couple weeks.
Also, with respect to Android. We've started on our Android app, but unfortunately, we have zero expertise with Android development and it's proven to be much more difficult than we ever imagined. I've personally been developing on web and iPhone for several years, so those were easier for us to implement. We are pushing really hard for a summer Android app.