Given the fact that USDC is fully backed by the dollar, it can be assumed that EUROC will also be fully backed by EUR, since they have the same issuer. The time-tested mechanism of USDC functioning does not require additional innovations, which will be transferred to the new EUROC stablecoin.
I would argue about the claim that the USDC is fully backed by the dollar. Since the last audit, this claim has been questioned and even Circle itself has amended its website to say:
In essence, they are writing that each of their tokens is backed not only by a dollar, but also by an asset of equivalent value. By this you can mean various securities, bonds, etc. Actually, I read somewhere that USDC has no more than 60% real fiat collateral, the rest is all in securities.