Don't think so.
As the co-founder of a somewhat substack competitor I'm not sure i can convince myself of the business case to go after Substack on the current size of the nostr network.
Also i believe substack allows BTC payments (partnership with OpenNode). And if that doesn't work there are substack competitors (beehiiv, ghost, ...) that do allow micro-payments somehow.
It's all possible with the current NIPs. You just need to build it! :-)