While you can check out this thread:
https://forums.flightsimulator.com/t/tutorial-how-to-link-skydemon-to-fs2020-for-free/232430?u=bertrandch
I choose the “not free” way to do it:
Price is anyhow not all that big and it offers a few options.
The base idea is to have a tool which connects to the Sim and broadcasts the data to your wireless network such that Skydemon or other mapping tools can get their positions from.
In my case, I wanted to be able to have my full VFR maps with all the interesting details available while preparing my real life flights. Linking FS2020 to my mapping device allows me exactly that.
Just a word of warning: in my case the default settings of the software was not working for some reasons, and I had to set an IP instead of leaving the broadcast settings. Nothing dramatic but it may prevent it to work for you too.
Also make sure to try the demo version first, as you can debug those issues before even spending 1$ more.
At the end of the day, I have my android device showing my VFR map, while I “fly” inside the Sim on my PC. Quite nice.