Over the years i've made a few attempts at using camera lenses for the iPhone with middling results. On balance i've found them a bit frustrating to use - either difficult to attach and keep attached to the phone, or requiring a special case, or having to fiddle with removing a case when i wanted to use it.
Anyway, it occurs to me that advances may have been made and perhaps there are some new options worth exploring and i thought i'd check in here to see what suggestions you may have.
I wouldn't be looking for any major kit, but i am toying with the idea of perhaps a macro attachment.
This was taken from that macro lens and some of my raindrops images🥰
Also, Moment lenses, they have a wide angle that is wonderful. ( https://www.shopmoment.com/lenses )