What's the use of a pan EU military when most EU members are already in NATO? Just to add Austria, Cyprus and Ireland to a pan EU force? Rather than that allow a share of EU funds to be used for members' militaries and adopt common EU military policies. Also incentivize EU members to buy EU military equipment using such EU funds.
The ability for EU common bodies to command the new army to defend their other members without being subjected to divide/conquer tactics from US, RU and CN.