Personally I disagree with sending any kit, the Ukrainian military has its own equipment (as well as what nato has supplied), the idea of sending pc's etc., irrespective of the brands, will be pointless if there's no armour to put in it.
As for mag carrying, better of with a decent quality satchel or similar, the only real hope for the untrained volunteer masses will be harassment & interdiction, essentially hit & run, traditionally in history those that operate in this manner, the ability to blend in to the population afterwards will make more of a difference than just looking the part.
Harsh when we're discussing "charitable donations" but true unfortunately 🤔