@jack@gardening Coir/coco fibre should be as good as any other soil/substrate- vermiculite, perlite etc (I prefer coir for it's provenance and natural look when mixed in soil outdoors--hate perlite for that reason; I also like zeolite or chicken grit- be sure there are no additives).
The only time coir may not be suitable is if you are trying to germinate something that needs natural soil chemicals to enhance germination- but no sterile media would have those, only natural woodland soil/duff.