Is skitarii equipment standardised ?

I've seen people shout that a skitarii vanguard can't carry a galvanic rifle and vice versa. But from what I understand, each skitarii is augmented differently, so I would understand if standardized equipment is given to skitarii just "stronger than a servant", but for those who are still sapient ?

Also, if skitarii equipment is standardized then why do alpha skitarii have different weapons from each other and why do cereberys sulphurhounds think they're in a western? (By the way, what do we know about the Phospore Blast Carbine? Can anyone other than the Sulfurhounds use it?)

Can't a Vanguard use a Galvanic Rifle if he thinks he's aiming better?