No anacharchist society could ever survive being in competition with a legitimate nation state with mordern weapons.

An anarchist society would need manufacturing capability to create weapons that would be effective against the enemies they faced (much like Ukraine's local drone construction is essential to their survival). That was an issue in the Spanish Civil war, especially as no outside countries were willing to help logistically except for the USSR, which had strings attached, and was mostly diverted to the Stalinist faction.

These two concepts are so incredibley far removed from each other

I don't believe they are. Rojava modeled its society on Democratic Confederalism as laid out by Abdullah Öcalan. Abdullah himself was heavily inspired by the works of Murray Bookchin, who advocated for a form of Eco-Anarchism, which Solarpunk itself is partly based upon.

I am not saying that Rojava is a solarpunk society, it is not, it's also not considered properly Anarchist by most Anarchists, but it is currently an existing society that at least is attempting to decentralize societal power in a meaningful way (to varying degrees of success), similar to the Zapatistas.

Also to be clear, my reference to Rojava in my previous comment about Community Defense related to how they had replaced law-enforcement, the primary subject of this thread.