I found the Kere server and it is a hardcore survival server but it plays really different.
There are no structures and no hostile mobs spawning so the danger is more about staying alive in hardcore while you explore and build.
The terrain generation is made to feel like continents instead of one giant landmass and there are a bunch of small features to discover.
It is on Java and it says version 1.21.11.
If nobody is online the server can go into sleep mode and you just wait in the lobby until it boots back up.
