Maaaany years ago there was a site that was showing the apps from Jolla Store for Jolla-C and if I remember right there was some basic search functionality. No ideas if it is still up and running or if the source code is available and you can make it run for other devices too.
Here, I did a little search for you: Jolla application Store - web version - together.jolla.com
One more: Web interface for the Jolla app store