Using iOS 7 in 2018

I'm trying to search for apps compatible with iOS 7, which I run on my iPhone 4. However, it is super difficult, as most apps seem to require iOS 9 or later, and there is no option anywhere to filter by iOS requirements.

Anyone else using iOS 7 in 2018? It feels, sometimes, like I need a support group! Upgrading to a new phone is not really an option for me, as I have been job searching for almost 2 years now (freelancing barely pays the bills) and I rely heavily on my iPhone 4 and my late-2009-era MacBook Pro to make what little money I possibly can.