Here is a awesome tool created by someone on github.
This is a small (unofficial!) weekend project I made to browse and install shell extensions without needing a browser, as well as to learn GTK4 + libadwaita.
I've been using Fedora Silverblue lately and have had a lot of trouble with installing shell extensions (flatpak browsers do not play nicely with extensions.gnome.org). I've always wanted to be able to install extensions from a native GTK app, so I decided to create this.
If you're interested, you can get it here: Release Initial Release (0.1.0) · mjakeman/extension-manager · GitHub (You'll probably need the "gnome-nightly" flatpak repo installed, see the release page for details)
Let me know what you think!
Edit: Extension Manager is now on Flathub.