Most brand ferts and DIY dry ferts are pretty invert-safe, in my opinion. Unless you dose large amounts of copper and other metals, then it's not safe. By the way, what is the temp of the tank? Mosses usually like cool temps around 74 F, in my experience.
cool temps and water flow. and free floating not attached to something.
I have a small hob refuge that plumbs back into my main planted tank. has 2 shrimp in there. free floating moss jungle and it grows plenty fast as well. around 76-78 degrees.
I have about 3 basket ball sized moss clumps free floating in a 120g gold fish tank, bare bottom with plenty of flow. Started out with a small bouncy ball sized trim from one of my other tanks. tank is around 72-74 degrees, plenty of junk from the gold fish.
I've found that the dry ferts typically used with EI dosing raise TDS dramatically, especially the salt based ones like K2SO4. For that reason I would start small and measure TDS to ensure whatever you choose doesn't have the same effect.