Hey there, welcome!
I may be wrong but I think that the ANT pool is just being distributed through PayForQuotes (same smart contract function that uploaders use to pay for storage). At least, that’s how I’ve always seen ANT come to me from running nodes (before and after Autonomi’s launch/TGE). I think it could be that they upload whatever random data, which (due to self-encryption) makes every node have an equal probability of being the one that’s closest to the address of chunks that are to be stored.
I’ve thought of similar approaches. A couple of concerns I have about your idea of one big pool is centralized management, the node not knowing whether the uploader is really paying their fair share for the particular upload, and also ensuring that nodes are getting rewarded for the time they’re online (and are not cheating/spoofing). Also currently, AFAIK there is no list of nodes.
One payments approach (which would require modifications to Autonomi’s source code) could be something akin to Bitcoin’s Lightning network. Rather than directly paying a node, there are trusted (staked) intermediaries that conduct lots of small transactions off-chain and settle periodically. Kind of like traditional finance, where there are banks (e.g. a buyer instructs his bank to transfer money from his account to a seller’s account at another bank, and the banks periodically settle their batches of transactions). There are other ideas being discussed in various threads (such as Autonomi Community Token Proposal).
Autonomi documentation mentions plans to have a “Receipt” form of payment, but currently details are scarse.