I collect comics digitally. Over the years I've tried a lot of readers - most of them feel like "open a folder and swipe." Fine, but not how I think about a collection.
I've been building Apex Comics for a long time, and it just went live on Google Play. I'm an indie dev and a comic reader myself - I got tired of file browsers pretending to be libraries, and apps that either lock basics behind subscriptions or treat your collection like an afterthought.