Hi
For a local non for profit I am looking for an alternative for our Facebook group. An easy to use interface with a mobile app is a must. We need to have a place to post important updates and have small discussions/polls. Being able to create events would be a plus. Does anyone know a good alternative? Thanks in advance!
Can you self-host, or are you looking for another online service? Facebook Groups is basically a forum when it comes down to it, and any forum software can do what you're asking. I really like Discourse. You can self-host it for free (well, whatever your server costs), they'll host it for free if you're an open-source project, or if you're a legal non-profit you can get 50% off their hosting for $25-50/month.
Ehhh unfortunately I don't think there is a good post-style alternative. Probably your best bet is a Discord-style multi-group-chat system like Revolt or possibly Matrix Element.