Time limit on non listed apps

Hi,

My son is watching the dudeperfect app on a firestick and I would like to set and hour limit.

Since the app is not listed with all the other apps such as instagram to limit can I manually add the app? I did notice the under usage -> categories-> Blogs & Personal Sites it has dudeperfectplus and a time pf and hour and 15 minutes.  I can limit that categorie but was wondering if easier way as there other apps like kiddio tv and others that are hard to find to limit.

Thanks