Gotcha, I'm thinking somewhat on those lines.

BitTorrent for the record uses blockchain as part of their wider incentive system, which clearly does oil the gears there, but blockchain wouldn't fly here. Here it would have to be e-cash based (and even then e-cash is still kinda hot-button here.)

I don't actually think unpaid relays work, just temporarily cost-covered relays.

If you implement a 1 sat per event toll, then it's a question of NIP-60 wallets as a default component of a Nostr profile (a lot to work still to be done there to give the user adequate contron) and a way for new users to get initially topped up.

The top-up part could involve an initial stash of cashu tokens P2PK locked to the relay operator, given out following the completion of an onboarding process that also acts as a screening process. For this you need a Nostr "first-top-up marketplace" of sorts, and a lot of specs to govern how the marketplace functions across the protocol.

The incentive for those offering first top-ups through such a marketplace is that users taking advantage can convert in some way (subscribe, etc.) when then run out of their initial Sats. So as a new user you can browse first-top-up options (or at least those that are visible to you based on xyz), see what you'll get, and pick an option, and go through the associated onboarding/screening. You get your first top up, and now you have a relationship with the topper-upper.

The topper-upper is incentivised to help ensure you have a good experience because, again. you can convert. The same as a freemium game being incentivised to ensure the player has enough fun to want to pay for something later.

The key is to make it so such top-ups can't be abused, or at least abused to a degree combatting the abuse negates the benefits. Again you need specs to prevent double-dipping and whatnot. And also time-expired top-up tokens, or perhaps a tiered-stash with upper tiered tokes being unlocked as a result of certain activity. All of this relies entirely on Cashu for the P2PK lock, expiration, condition setting and such.

And then there's the whole regulatory side, which, leave that for now.. But something along the lines of a protocol-defined first-top-up marketplace.