I can perform search queries on the forum by visiting this article and tapping on the search link each time for the search page to pop up but this is inconvenient for a mobile device user.
I searched the forum on how to reach the forum search page from within the Android app menu or generally its user interface to no avail.
I could not find any menu item for the search page. Did I miss it or is it not implemented. In the latter case, a support update is needed and it is very easy to do I believe.