I think nostr.wine filter does something like this. It will publish and pull from the free relays, but filter spam. At least that's my understanding of it.
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Thanks #[3]
You can read more about it here: https://filter.nostr.wine
We want to keep nostr decentralized, not move to one giant hub. Filter is a way to use only 1 relay on the client side but receive and publish to 10+ large public relays at all times.
You can choose to filter content based on either your follows+their follows or use the global=all parameter to open your network further. It’s all in the readme! Let me know if you have questions.