Basically a re-invention of the early 2000's Hamachi app?
I think I might have used Hamachi once or twice to play a network version of Age of Empires over_the_internet long before this was a standard function in games :)
I just Ducked for Hamachi VPN and it still exists, see https://vpn.net
I believe Hamachi was mainly a level 2 VPN, perfect for transporting IPX, which was really mainstream for LAN games of the 90s.
This seems to handle layer 2/3 since they mention support for TUN/Tap interfaces, but I guess 99% of people will just create IP tunnels, layer 2 is not the hot thing anymore.
Also, Hamachi was not decentralized from what I remember.
I just Ducked for Hamachi VPN and it still exists, see https://vpn.net