You’ve probably seen these type of baskets made from coco.
This product has been used for many years but is recently gaining popularity and is beginning to replace peat in some places.
I doubt it will ever replace rockwool or leca completely as it is not as sustainable.
Some people use it with peat, soil, rockwool, leca, perlite, a combination of those or just by itself.
It’s an organic substrate so plant roots love it as well as beneficial enzymes and bacteria.
It’s known as a better substrate than peat but more expensive as well.
There are specialized nutrients made especially for coco coir.
It comes loose, or as bricks that expand when watered or as mats, pots etc. much the same as peat is used in different ways.
It also is reusable but only for a few times then it can be composted and used outside.