The QT client for Matrix is called Nheko: https://nheko-reborn.github.io/
There's a client in just about every toolkit. Just takes a cursory internet search...
Unfortunately, they still use libolm[1] for e2ee which is deprecated[2] and has known security issues[3]. The maintainers appear to not be interested in switching to the newer Rust-based library. Matrix argue that the timing channel attacks are not possible over a network, but the history of timing channel attacks argues that this very few protocols are this fortunate (most people thought timing attacks against TLS were impossible too, until someone bothered to attack them).
Yeah, although Matrix is theoretically about being an open protocol supporting a range of clients and servers, in practice it winds up being heavily skewed to just Element/synapse. I think this is partly because there is still too much churn in the protocol. A decent amount of that churn is improving things, but it still makes it too hard for average-joe devs to keep up with what's hip. I don't think there's much chance of a real menu of feature-rich clients until the protocol becomes stable. Unfortunately, I don't foresee that happening soon.
AFAIK none of that churn is around functionality that actually matters that much to end users, however. Certainly nothing as important as “working clients”.
There's also a really great Gtk client called Fractal from GNOME; it uses the same matrix-rust-sdk as Element X: https://gitlab.gnome.org/World/fractal.
Meanwhile the plan for Aurora (Element X Web) is to run it in Tauri or similar to placate all the Electron-haters: https://github.com/element-hq/aurora
There is also Neochat from KDE, not fully featured like Element and E2E Encryption still experimental the last time I checked, but it is a nice alternative if you want a non-Electron client.
[1]: https://github.com/Nheko-Reborn/nheko/issues/1786 [2]: https://matrix.org/blog/2024/08/libolm-deprecation/ [3]: https://soatok.blog/2024/08/14/security-issues-in-matrixs-ol...