Good question, let's try to answer it. Suppose OP believes they have a serviceable replacement in place. What arguments could they use to convince their communities to switch to it? Here's some ideas:
- No ads.
- Free, even for business-use.
- No algorithm interfering with visibility.
- It's usable by community members who do not have a Facebook account, for whatever reason.
- Allows for more free-form content.
- More choices for content delivery format & notifications (say, email, text message, newsletter links).
Maybe you can come up with some. What would you find to be a convincing argument to switch to a community-owned organization platform instead of Facebook?
Hello, it appears you've never even ran the most basic internet platform before in your life.
Simply put you have to ask the most important questions first, then build an app backwards from that
1) How will it be paid for
2) How will it be moderated.
So, you've already failed number one. You have no means to pay for it.
Then you failed number two. If it gains even a modicum of popularity it will be completely and totally over ran with spam.
Who pays for it?