When I first started growing seedlings I tried an assortment of homemade potting mixes...
...cinder & peat moss
Each had a drawback that didn't work well for me. I'd say that the cinder & peat moss worked best, but the cinder I had was too coarse. I needed something finer. And the pH was way off, so it only good for starting seeds.
I could have kept experimenting but I needed to start getting serious about growing food. So I looked to commercial potting soils, something with an established track record. By shear luck I stumbled upon several bales of Pro-Mix that someone wanted to sell. I jumped at it. I was able to get a pallet of Pro-Mix MP, which is an organic version. The basic difference between BX and MP is that BX contains vermiculite and a wetting agent (MP doesn't), plus MP uses about 30% coconut coir in place of spagnum moss. MP cost significantly more than BX, and another drawback for me is that it dries out quickly. I had to water seedlings daily, even on cloudy days. When I ran out of MP I looked around and settled on Pro-Mix BX, the version that my local Ace Hardware sells.
BX is not considered "organic", I guess because it contains a wetting agent. This doesn't bother me, because as I see it, organic gardeners use Dawn dish detergent as their wetting agent and it surely isn't organic either. I amazes me how gardeners that are so wrapped up in being organic will turn a blind eye to using Dawn, cardboard, newspaper, old carpet, regular garden hoses, plastic rain barrels, etc. All these have traces of chemical contamination and aren't organically "clean". But as I said, it doesn't bother me. Realistically, I can't totally avoid chemical contamination in my life. Not even the air I breathe is chemical free. I just try to be reasonable about things, not fanatical.
So my current potting soil is Pro-Mix BX.
Some day when I have the time to fiddle around, I plan to come up with a homemade version. In the end, I'd like to be more self-reliant and have my homestead provide for itself the best it can. I have access to homegrown fresh spagnum moss, though I don't know if that is something to use. I'd have to mix it with something else. I also could gather lots and lots of coconuts locally, which couod be made into coir. But I would have to figure out how to do that. I have volcanic cinder which I would need to clean, sterilize, and sift. I have compost & garden soil which would also need to be sifted and sterilized (fungal diseases abound in the tropics). And I have easy access to lava sand. It's a lot to be figured out. As I said, I don't have the time for that right now. But my gut instinct says that lava sand or volcanic cinder, along with fine high nutrient compost might be the ticket.