Are the few thousand soldiers they would get worth the possible loss in support/morale by announcing this apparent desperation to the world? Things must really be tough on the frontline right now.
They are tough and you would make the same decision - Ukraine needs every trigger finger it can get - we know the horror of the alternative - it’s not a terrible look, it’s a required action - war is nasty, Western Europeans take note and toughen up
Petty crime, non violent or non sexual offences - they can volunteer
