Apps similar to wxPython include Qt, which is open source with a free version. Other options are GTK, Kivy, wxWidgets and Cambalache. There's no shortage of Software Frameworks like wxPython, with more than 25 alternatives for Linux, Windows, Mac, Android and self-hosting.
Gio is a library for writing cross-platform immediate mode GUI-s in Go. Gio supports all the major platforms: Linux, macOS, Windows, Android, iOS, FreeBSD, OpenBSD and WebAssembly.
Repose is a Rust UI framework with a Compose-like programming model. It's organized as a small core (repose-core) plus higher-level UI/layout (repose-ui) and platform runners (repose-platform) that currently target desktop (winit) and Android, with web support.
