Iranian weapons can go through Iraq + other ways of smuggling + looting of government weapons. Mercenaries also usually aren't the hardest fighters since they are only doing it because they get paid. These countries lost to the Houthis on foreign soil even though they can use much harsher methods and indiscriminatory bomb civilian targets, they will not be able to stop an internal uprising.
That's true, however some of these mercenaries have experience in other conflicts, they can potentially be troublesome during a war. but like Machiavelli said on his book
> "They have no love or other motive to keep them in the field beyond a trifling wage, which is not enough to make them ready to die for you."
>"If they are skilled, you cannot trust them, for they will always aspire to their own greatness... but if the captain is not skillful, you are ruined in the usual way."
And we can see how mercenaries can be a double edge sword in Modern conflicts, like for example in Ukraine and the Wagner rebellion, they were useful for taking territory like bakhmutt but then they rebelled against putin.
Iran if they have enough money they can simply just buy them off, buying a single mercenary in their army can cause enough trouble because they can easily sabotage their platoon or worse their own division.
