Is this the same as coco coir? I usually use cypress and a sphagnum moss mix but I saw this today and was curious. The fact it says its bad for dogs has me doubting it.
The compound they warn about 'theobromine' is the same compound found in chocolate that makes the thing commonly consumed by people (Chocolate) toxic to dogs.
Even though they are calling it coco something does not mean it comes from coconuts' shells, but perhaps coco nut, as in what chocolate beans shells are. So, I would agree maybe not something to experiment with as a tortoise substrate unless someone offers a specific positive experience.
Coco coir is the stringy part of the exterior of a coconut shell or also from the other side, the inner part of the coconut husk. I use coconut husk chucks and orchid barks which is ground bark from fir trees used to grow orchids in. Then there are several hard-wood mulches used by people, the most common and considered the best is Cypress.
In this diagram the dark circle is the shell itself. The coir is the more fibrous loose stuff in the husk and it has been processed so it can be compressed into bricks. Coco husk chunks are larger pieces and don't get 'muddy' like the coir. They are essentially the same thing.
The shells of cocao beans is what it looks like in the image when I look at the content of the bag you show in your OP. Not the same stuff that comes from coconuts, but does contains the compound that is toxic to dogs.
I use cypress but coco coir and orchid bark is impossible to find. I was just looking to possibly switch it up but certainly not at the risk of my torts.
If you haven't already tried:
Garden Stores (its sometimes used as a renewable alternative to peat)
Hydroponic stores (growing medium)
Online (I've done eBay in the past; Amazon if you can find it with free shipping. Shipping may make it cost prohibitive to buy online)
It's also used as bedding for worms (vermicomposting) but I've never seen it marketed for that IRL, just online.