Also found a solution which I've outlined here:
In principle steps:
1) put all your "communicators", all software that requires screen sharing (slack, google meet) into some seperate, micro run time that rendering with help of some X server on your host. I'd suggest https://github.com/mviereck/x11docker as it's super light weight and convenient. Also put a remote desktop client software of your choice into that run time entitiy
2) Spin up some remote desktop serving agent on your host, my choice was https://github.com/any1/wayvnc (requires sway 1.4 though!)
3) Connect from your runtime via VNC (or whatever protocol of your choice) to your host running sway.
4) Now you can share screen in your micro runtime the screen showing the host VNC session
Effort is light and more stable than some hack until wayland native screen sharing matures.