There is an influx of new members to a group I own, and we have a weekly vote, usually on Discord. However, with so many members, we’re running out of emojis to use. As an alternative, I suggested using the Developer Forum. However, it seems you must be a member to vote on a poll here.
Is there any way to make polls public?
I don’t think that’s possible but there are many great polling options. They’re just one google search away 
Why not use Google Forms? Discord isn’t meant for voting anyway. Make sure to require certain fields such as Discord Tag and Roblox Username to avoid botting and duplicate votes.
As an alternative you could look into strawpoll.me (I’ve used it many times in the past, it works in a pinch if you want to make a quick poll) but I agree with @wevetments, Google Forms is pretty flexible and may be better for your use case.
You could use strawpoll.com as their service also comes with api that you could use from a Discord bot, website, or in game to create polls, as well as read results.