macOS - Windowed mode with no title bar

Trying to build a MacOS app that will share the screen with another app, but while I can get the app to open in Windowed mode rather than the default Fullscreen, and I can set the size in Blueprints, the window always has the default Mac title bar.

I have set the “Borderless” window option in game settings.

In Windows I can make the Windowed Fullscreen option work, but on a Mac it seems the title bar is always there.

Does anyone know of an approach that would give me a true borderless, chromeless window in MacOS?