If you squint, Godot has a cross platform hardware accelerated GUI. The editor is itself, in a sense, a Godot app and has builds for VR Headsets, Android, web apps, all the usual platforms. The extension api works pretty good too for Rust, and Rust itself has a fantastic cross platform and WASM story. It might be cursed, but it can get complicated stuff out the door and in anyone's hands fast.

edit: they also recently created libgodot, which flips the model. Your application owns and controls whatever components you want to pull from Godot. Being open source and relatively legible of a code base you could presumably strip out a lot you don't need.