TL;DR maybe use something like 0bin to host it relatively securely on the internet.
If I would host PII publicly to be “only accessible via the chip” I would make sure to “hide” the file on a server, like make it a looong weird name and no directory listing on the server.
This is not very secure, but in essence it’s the same as storing text, if the server doesn’t get hacked completely, only people with the chip know the url.
You could even store it encrypted on the server and have a password in the hash part of the url (doesn’t get sent to server) and then have it decrypted on the client. That way not even the server provider sees the content, like 0bin does it. But idk if 0bin can provide the uptime such critical data needs.
Okay now I want to make a client side encrypted popl.