If you are any kind of a do-it-yourselfer, you can make yourself a scope for your phone from an old laser pointer lens. It is not perfect but I was using it today to get some close-ups of Rhododendron anthers for a casual observation that was connected to a bee observation.
https://www.inaturalist.org/observations/118294157
I was mentioning it before in this post: https://forum.inaturalist.org/t/life-hacks-for-naturalists/4636/131