what is the best vermiculite to use in my bearded dragon cage?
yes coconut fibre is, also vermiculite, perlite, sand, hydroton,rockwool
You mean cocoshell fibers? Yes, they could replace bagasse in a soil-less mix. But most potting soils are actually soil-less mixes. Why not just get some? Using either bagasse or coconut fiber by themselves would NOT make a good planting media.