https://www.minecraftforge.net/forum/topic/50929-getting-ping-to-a-server/
From what I read there, it's really simple to get the ping from the client side.
I don't know if 1.15.2 changed that, but this isn't what I'm looking for since it uses Minecraft.getMinecraft which is client-side only.
Is there a simple(r) way to get the ping of a player from the server side?