And for those not seeking to limit their exposure, this extension provides a substantial list of porn websites to choose from: https://github.com/dikshantrajput/noFap/blob/main/public/lis...
I don't doubt that there's a lot more out there (10x yes, 100x possibly, 1000x unlikely imo), but I think tens-of-thousands is enough to capture almost all of the significant ones that get any traffic and will be around for longer than one or two domain renewal periods.