This datapack aims to make a lot of unobtainable items obtainable in Minecraft skyblock. Most of it's features are meant to be used in combination with Skyblock Standard by BPR02. Not all items are obtainable, mostly due to them not being that useful in skyblock, but it improves the obtainable item count a lot in Skyblock.
You can try to figure out how to obtain all these items on your own, but there is the wiki if you get stuck on figuring out some of the mechanics.