There's not a Linux ABI emulation layer but it is running on top of a Wayland emulation layer, instead of using the Be GUI API directly (as the Qt, SDL, and Java Swing ports do.) That does make a difference, especially around stuff like keyboard handling.
Yeah, skimmed through them and mixed up the wording. It says "port now is built atop [the Wayland compatibility layer] for both features and performance reasons", remembered it the other way.