Currently polls are closed-ended, meaning that the choices are pre-determined.
Is there possible to have “open-ended” polls, with an extra choice allowing the user to add new suggestions? Something like an Others: line with a text-box that the user can enter new texts.
Nothing like this exists at the moment, but you could onebox a 3rd party poll that possibly supports this. Or you could make a topic and use “likes on post” to somewhat simulate this.
One that seems to onebox very well is
Example:
Closed in favour of Let users add more poll options while the poll is running