I found LegionCraft and it is a OneBlock survival server where everything is about building up from a single block and pushing your island forward.
There are challenging bosses and when you beat them they can drop keys for rare loot. You can use keys on crates to get gear and rewards.
It also has chunk hoppers so you can automate parts of your island. The server says it is not pay to win so it feels more fair while you build grind fight and loot.
