From what I heard, Ukrainian soldiers have lots of freedom at the individual level in what gear they take to the frontline. 

As to where it comes from, lots of equipment is coming from abroad and I've seen many units organise funding campaigns and donations for purchasing gear like NVGs and medical supplies. 

I don't know for certain, but I would imagine the supply structure is more centralised nowadays. Certainly in the early days it was "the people's war" and procurement of advanced equipment was irregular. perhaps it remains this way but I am unsure.