If you strive for pure decentralization and autonomy on the network level you can't stop at mesh networks though. Mesh networks still rely on centrally controlled undersea cables and / or satellites to stay globally connected. You'd need physical alternative infrastructure to connect the world's continents.

That being said, running on centralized ISP infrastructure does no harm to the permissionlessness of a cryptocurrency, given that its network requirements are modest enough to reliably work on mesh networks or other alternatives. Put differently, an off-road vehicle being able to drive on regular roads does not make for a lesser off-road vehicle.

Regardless of that there's various efforts by Bitcoiners to circumvent centralized ISPs. There's Bitcoiner's using mesh networks, as mentioned by ETFbitcoin. There's Blockstream satellites (ie. an example of intercontinental physical alternative infrastructure -- run by a centralized entity obviously, but if Blockstream can put Bitcoin satellites into space, so can other private entities). There's even been efforts on Bitcoin transactions via radiowave transmission -- and that's honestly as decentralized as it gets.