Starry Skies is a dimension mod that adds a dimension with that same name (and a matching Nether and End!). It is inspired by the "planetoids" world generator by Seibai for Minecraft 1.2.5 back in 2012 - although a LOT more extensive and fully data driven.
The Starry Sky dimension consists out of never ending floating spheres floating in the sky. They can be filled with precious ores or dungeons. But watch out! If you're careless you could very well burn in lava. By default Starry Sky generates with a water floor, but ground height and blocks are completely configurable, so if you prefer more of a skyblock experience: no problem!
Pretty much everything vanilla can be found in Starry Sky, too. Including dungeons, stongholds, end cities and so forth.
To switch from the Overworld to the Starry Sky build a portal out of packed ice and light it with a Wind Charge (NeoForge) / Flint & Steel (Fabric). Scary Sky ("Nether") and Scarcy Sky ("End") can be accessed like their vanilla counterparts, just from the Starry Sky dimension.
Take a look at my other mod GlobalSpawn to configure your spawn dimension. At x:16 y:90 z:16 will always be a wooden sphere, so that will be a great starting point for your adventure.
Alternatively you can use a data pack to replace the vanilla dimension generation with Starry's altogether!
