This would make actual sense if there was an actual european army that was commanded by EU institutions and those same institutions had the power to declare war unprovoked. As there isn’t at the moment, the only war EU citizens will be drafted to is the one that falls upon member countries’ doorsteps (or upon NATO members’, if your nation belongs to such alliance) OR if specific member states that you belong to decide to be the aggressor in future conflicts. Unanimity allows bad actors such as Orban to abuse their veto powers against the interests and progress of the majority of the Union, which holds back our collective response to an ever changing geopolitical landscape, which in turn might leave us vulnerable to being attacked or strong-armed into a lopsided, paralysing dependence (for instance, on Russian energy or US defence). And that might be the one thing that gets us drafted into an actual war, only not one we prepared for, and with an emboldened enemy against an EU frozen in place by one member state acting on the aggressor’s behalf.
Why would we suddenly follow Germany’s stance and not Spain just because unanimity is gone? We would likely follow a qualified majority or supermajority, just as other aspects of legislation (perhaps even draw out higher thresholds for voting). If the majority elected to take a position against Russia (or for Ukraine, if you will), then it isn’t anything but counterproductive, that we remain in a political quagmire because of one individual exercising veto powers. If the majority elected to take a different approach to foreign policy towards the US, then it would also be frustrating if it was up to an individual head of state (sponsored by the US regime and Heritage Foundation, no less) to veto our collective action. This won’t get us moving at all.
On regards to corruption, the EU already witholds funding from Hungary on account of rule of law and democraric backsliding. We can’t hold a position to be for individual sovereignty when it comes of foreign policy and at the same time demand a supranational organisation to come in and prosecute national leaders, who were still at some point in time elected by their people fairly. As you’ve said, we aren’t a federation yet, if the EU prosecuted another country’s leader, it would be a massive overreach and a tremendous cry for sovereignty in jeopardy.
On a personal note, I would be happy with both scenarios playing out, and personally feel federation might be a way to survive a growing upending of rules-based order in the world.