Instagram Story Downloader

I am Looking for Custom Instagram story Downloader for my web app. I am building a PWA(Progressive Web app), Which take username or URL from user and shows all the stories from that account. User can select and download whatever story they like. The script should be faster and less complicated.
+ Plus point for PWA experience
++ Plus Points for Anyone who knows Dart as well for Flutter design and Implementation
+++ Plus point for knowing/Working deeply with Web Share API