And who is in those councils? Elected officials?

No, just more citizens of that community. As an example, imagine instead of different districts of a city just electing some non-recallable representative to make decisions for them in a city council, that instead different neighborhoods got together for meetings to collectively debate on what their part of the city needs, and then once that's decided by consensus, they can then elect a recallable delegate (distinct from a representative) to bring exactly those needs to the wider city council of delegates, who then organize solutions to those problems.

There is a fundamental difference between our current systems of centralized representative democracies and bottom-up federated communities of delegates. The latter is far less effected by corruption, and prevents a top-down government that can dictate to the people without their explicit consent.

You're right that Rojava is not Anarchist, but it was at least inspired by Anarchist theory (Murray Bookchin), and does act as a good example of at least the concept of federations of smaller communities working together, which is why I reference it.

Without that support it probably would’ve been crushed years ago

The US did abandon it years ago, but it was able to successfully hold the land it had, and even spread further on its own despite constant attacks from Turkey. Only very recently due a renewed effort from the new Syrian government (which allied with Western powers) combined with much stronger attacks from Turkey have they lost land.

decentralization doesn’t magically eliminate corruption.

I never claimed it did. But it does make corruption far more difficult take hold, and far more limited in its area of influence. Instead of bribing a handful of the people who hold the keys to power, you'd then have to bribe an entire community to effectively corrupt them. Any individual delegate elected to some position who does become corrupt can be immediately recalled by the community if the corrupt delegate no longer adequately performs the duties assigned by that community.

Historically that often turns into local strongmen, militias, or patronage networks.

This usually occurs due to an initial imbalance of power or control of limited resources that is able to be exploited. If every citizen was militarily capable (such as in Switzerland), and each community and person helped each other with mutual aid, resource scarcity would be so reduced that it would be difficult for a strongman to convince others to join him (what would he realistically be able to offer as reward compelling enough to start shooting their neighbors, when they already have their needs met?), especially if the local populace was not significantly weaker militarily than the strongman and their goons.

Right now under centralized democracies, there often already are unelected militias (police forces) which operate on behalf of strongmen (wealthy elites and their interests, under the supposed control of corrupted politicians who are in the pockets of the elites). The elites pay almost no taxes, while the middle class and poor take up all the slack, which effectively becomes an unfair patronage network.

At some point you need mechanisms to coordinate decisions across thousands of groups

Which was effectively done in Catalonia, with many committees of delegates from various groups, all of which worked together pretty damn well from all accounts. If you want to read how all of that was done and and how well it performed in practice, then I highly recommend reading Sam Dolgoff's The Anarchist Collectives Workers’ Self-Management in the Spanish Revolution, 1936–1939.

And mutual aid doesn’t remove incentives for conflict either. Scarcity still exists. People still compete for water, land, energy, and strategic resources.

The entire point of building a society atop the principles of Mutual Aid and Anarcho-Communist principles is to effectively eliminate the artificial resource scarcity we currently live under. We currently have the technical capability to provide to virtually everyone on the planet enough food, water, and housing right now, even without a star trek replicator, we just don't mostly because of profit incentive, and because a subjugated populace is often more conducive to the interests of the elites.

If decentralized societies consistently lose to centralized ones, that suggests centralized coordination has real advantages in defense and large-scale organization.

Many centralized states also consistently lose to other centralized states. The Axis powers were all centralized, but lost to the allies. They didn't lose because they were centralized, they lost because they couldn't support the logistics required to win due to circumstances unrelated to their form of government. The same was true of the decentralized societies, they didn't lose due to some flaw in their choice of societal structure, they lost because literally every other state in the world saw them as a threat to their hold on power.

The tankies betrayed them and crushed them because they were ultimately seeking to become dictators, not liberators, and thus a genuine anarchist revolution is a threat to their hold on power.

The centralized capitalist countries are just as concerned of their hold on power, and the elites are especially concerned with perpetuating capitalism above all else, so they most certainly aren't going to assist a movement that is explicitly against the interests of the capitalist elite.

Had an Anarchist revolution occurred in the US due to the great depression (instead of FDR putting a cap on it with labor reforms), then the Anarchists in Spain could've had a powerful ally to supply them logistically, and they could've won, similar to how the USSR was able to logistically help tankie revolutions into succeeding.

You can call them councils or federations instead of ministries, but functionally they’re doing the same job.

A bottom-up federation of recallable delegates is fundamentally different in practice to a hierarchical centralized representative democracy.