Wood products usually consist of partially decomposed waste wood and can include wood fiber, composted bark, sawdust or wood. These products have good drainage and low pH, but they require a higher nitrogen fertilizer than peat. One problem with wood is that the material is not consistent from batch to batch and you have no idea what chemicals might be included with the waste wood.
Biochar is a product that is produced by heating organic matter to high temperatures (300-500°C) in the absence of oxygen. The result is a very stable form of carbon. Biochar has been tested as an agricultural additive to soil and has shown mixed results. Because of this and regulatory issues, commercial biochar is not readily available. Even if further testing is positive it will probably only play a minor role in media as an additive.
The best peat for horticulture comes from sphagnum moss bogs. The sphagnum moss grows in the bog and accumulates over time forming peat moss. The harvested live plants, called sphagnum biomass, is a good alternative to peat, but it is not readily available. Sphagnum farming is very new and can’t be considered an alternative at the moment, but long term, it might turn out to be the best alternative.
Coir is made from the husk of coconuts and is the waste product remaining after the coconut is harvested. It comes close to having the same properties as peat moss. Coir may be a suitable alternative to peat for pot culture, but it also has environmental issues. Based on current data, it is not more environmentally friendly than peat. The environmental cry to replace peat with coir is unfounded.