Anonymous surveys, with a clock on them.
Make a poll or feedback form. Share one link. When the time you picked is up, the survey and every response are deleted.
What's actually anonymous about it
The database has no column for your name, email, IP address, or user agent — there's nothing identifying for the survey owner to look at, because the app never collected it. Free-text answers are encrypted in the browser before submit, but if you write your name into a comment, the admin can still see it after decrypting.
QuietPart doesn't try to prove who has and hasn't voted. Doing that well requires tracking identity, which would defeat the point. Duplicate prevention is intentionally weak.