New Future owner and just had some general questions

I'm confused when it comes to feeding on certain substrate. Now from what I can tell it's ok to feed them in there cage but between eco bark or cyrus mulch, what might happen if they digest one of those? Also which is better to use as far as feeding wise and humidity?

If the prey is dry the amount of substrate that will stick to it is minimal. Ingesting a minimal amount of substrate will not do a thing to them. Its no different from them eating in the wild.

Either of those substrate can be feed on with ease. If I only had to pick between those two I would vote for cypress mulch.