Hangs under sway
Putting exec big-launcher in sway's config has no effect. Starting it from a terminal emulator also doesn't draw any UI, print any errors or quit.
It might well be, that tiling wms have too many opinions on window positioning, but then I'd expect big-launcher to give up, and let sway and the user manage its window size.
Before sway, I used it under cage-kiosk, then settled on labwc. As the machine is meant for this single purpose, I don't really have much of a preference, and this isn't a high priority issue (for me). If you don't end up supporting sway, or if it needs extra config to get it working, the README would benefit from a section about this.
This is possibly relevant? https://github.com/libsdl-org/SDL/issues/9271
I just ported the project to SDL3. If you're still interested in this program, could you build and see if the issue still occurs?