If someone donates me Nexus 7, then I can probably port/compile hostapd and make some GUI to it for Harmattan. But as currently all my devices work with adhoc, so there is no reason for me to try getting it work...

But maybe someone else will do such an app someday.

Maybe you should make bug report(/feature request) to nexus/android bugzilla and ask them to support adhoc in their future firmware versions.