Today I learned, that IntelliJ has support for Wayland Compositor since version 2024.2, so seems like im rather late to the game.
Simply go to Help > Edit custom VM options and add -Dawt.toolkit.name=WLToolkit.
For me it so far works nicely. And the issue of some overlay windows (like object inspector) not being resizable in Sway … are just gone. Yay 🥳