This is a feature that the customer needs to implement. I don't see the need for a PIN. But notifications are a bit complex, as they require customers to be connected and receive notifications from numerous relays 24/7. The data consumption of cell phones will harm the battery.
Discussion
Is there any alternative? I saw public and private bookmarks on #Amethyst. Are they standard feature? Or their own implementation? Because I didn't see my private bookmarks crested on Amethyst show up on #Yakihonne.
I don't know how Amethyst works. Maybe nostr:nprofile1qqsyvrp9u6p0mfur9dfdru3d853tx9mdjuhkphxuxgfwmryja7zsvhqpzamhxue69uhhv6t5daezumn0wd68yvfwvdhk6tcpz9mhxue69uhkummnw3ezuamfdejj7qgwwaehxw309ahx7uewd3hkctcscpyug can help
We still use an old event kind that allows you to have multiple bookmarks lists.. :( we have to migrate to the newer ones that is just one list per user.