Run X11 VNC session under Wayland

I have a proprietary software that works fine under X11. But I want to use Wayland, since everything is so much faster under Wayland for me. But this application I want to use crashes under Wayland when I use one option (normally it works OK, but this one option which is important for me crashes).

Is it possible to somehow use this one application under X11 while I use Wayland? This application can be on a different “screen” (ctrl+alt+f2, ctrl+alt+f3, etc). Do I need to set up multiple display managers, one for KDE Wayland session, another for i.e. X11 Fluxbox session?

Or, another idea, can I for example set up a virtual X11 session only for VNC server (Xvnc), and from the Wayland desktop connect to this virtual VNC server and use my app run on a real X11 server? This application would be constrained in a VNC window, but that’s fine.