Aviary is a beautiful Twitter client built with iOS design guidelines in mind. It's simple enough to pick up and use immediately, and powerful enough to tweak it just the way you want. Built for iOS 14 and contains widgets, amongst many other great features!
Memplace is an AR iPhone app for leaving short notes around your space based on the “Memory Palace Technique”. Spatially organize things to help jog your memory later. Memplace is definitely experimental right now, so looking for your ideas and feedback.