I have found that OpenLP 2.4.6, as installed from snapd on the Ubuntu 20.04 works great. In fact, it will use 4K projectors (HDTV) in real resolution of 3840x2160. The Live Preview panel needs a fix but the lower screen is ok and it works great. I'm using an Inspiron 15 3000 Series Dell laptop with i5 processor and it's quick. I love it.
I have Windows 10. However, I installed Ubuntu 20.04 in dual boot mode and it works great.
In Windows 10, OpenLP 2.4.6 works great with VLC 3.0.8 Vetinari (vlc-3.0.8-win32.exe downloaded from http://download.videolan.org/pub/videolan/vlc/3.0.8/win32/
The advantage of Windows 10 is that in a desktop right-click I can "Connect to a wireless display" but only at a maximum resolution of 1920x1080 (FHD resolution) at the HDMI output of the laptop. (NO HDMI CABLES TO PROJECTOR)
In Ubuntu 20.04, OpenLP 2.4.6 works great with VLC 184.108.40.206 Vetinari (install from "sudo apt install vlc") Note: you will have to uninstall the VLC 3.10 that comes with Ubuntu 20.04 in the snapd, before installing the VLC 220.127.116.11 Vetinari.
The advantage of Ubuntu 20.04 is that I can connect automatically connect at 3840x2160 (4K resolution). HDMI cable needed but HIGHER RESOLUTION REALIZED.
I hope this helps someone.