The "Well-regulated militia" though is drawn from the citizenry. Therefore the citizen must be armed FIRST, then the militia, whatever the needs are, are drawn from them. This is why the complete amendment says
A well regulated militia, being necessary to the security of a free State, the right of the People to keep and bear arms, shall not be infringed.
So THE PEOPLE (i.e. all the citizens) need free access to firearms, such that the militia, whoever it maybe, can pull folks in who are already equipped and ready to be trained.
Kinda hard to honor the Constitution if you require folks to be trained first, only then to be 'allowed' to buy/possess firearms. That leads to gatekeeping of an elite "militia" who can then oppress the unarmed populace, which we see in COUNTLESS countries throughout time.