nixos-appstream-data VS Relm4

I don't plan on it at this moment, however, if someone finishes the packagekit backend for Nix, the appstream data I'm working on collecting would work to display icons and screenshots. Also if someone who knew qt/kirigami development wanted to make something similar to nix-software-center, the backend tool that reads and modifies configuration values is a separate project: nix-editor, and I would be willing to help with any issues that arose from that.

Currently, metadata is stored on my NixOS Appstream data repo

There is Relm (https://relm4.org/). Which is in Rust is just GTK (through it's Rust bindings) with a nice reactivity layer on top.

I’d recommend you checking out https://relm4.org if you know a little Rust. Relm4 is currently the easiest and most intuitive way to write GTK

Relm4 might make your migration easier. It has factories which make it easy to create lists (both sync and async) and recently added TypedListView as another useful abstraction over pure gtk-rs. There is a lot of potential in Rust + GTK, you just have to find idiomatic abstractions.

Did you try Relm? It's an implementation is the elm architecture (think react) on top of Gtk. Given your experience with Gtk it might suit you really well, as you can even take only parts of it and continue using bare Gtk for the rest. Give it a try!

What about relm4? Is it generally feature complete? Can one use relm4 for most things, and drop to gtk4 for the oddball task that is not supported?

https://relm4.org/

Using this example: https://github.com/Relm4/Relm4/blob/main/examples/simple.rs

What advantage would this Rust crate have over Relm4? It seems pretty similar to me, save for the property based syntax that Forte has, instead of the set_* ones used on Relm4.

If you like Rust I recommend Relm4, one of the best experiences I’ve had with a framework tbh, be sure to learn gtk-rs first.