The Qt World Summit will take place on May 6-7th, 2025 in Munich, Germany.
Some days ago the Qt Group posted a Call for Papers for live talks. They are looking for speakers, collaborators, and industry thought leaders to share their expertise and thoughts on a wide range of topics you think are important to the community. As far as I can see they care about Accessibility and UX (see Qt 6: Accessibility Overview, Qt UX Page), but I personally don’t know much about its maturity.
Qt is for instance used in the KDE Desktop Environment and the VirtualBox GUI.