It's not my favorite solution, but you might be able to talk people into using NextCloud, and that would cover a lot of those bases.
Discussion
The problem you'll face with that is that Google / FB obviously work better. I selfhost Nextcloud and I like it, but unless people are made aware of why you shouldn't use centralized, Big Tech stuff all they'll see is a subpar alternative.
Why get a NC account when everybody has FB / Google already and it offers a beautiful garden? Most people don't know that the garden is walled, but of those who know or are made aware only a small fraction will care.
I'm in homeschooling groups. I haven't tried to descentralized or FLOSSify them. I had little success with friends and family in the past and I'm jaded...
That being said, nostr:nprofile1qqsd3uut39959acqsvzua0chkjyj2e20y2ccp3vxrwq3g8uqenmjsjqpz9mhxue69uhkummnw3ezuamfdejj7qgkwaehxw309aex2mrp0yhxxmmfdehhxtnfduhszxthwden5te0d4ex2cmgv4jhxefwxgck66tv9ekk2tcxnhsg6 if you plan to create some sort of homeschooling platform based on free software, I'd be happy to help.
This is all true, for sure. I'm setting a goal of 1. If I can get that, I'll call it a win. I can probably offer a class on basic privacy and security at the co-op to gauge interest. Open it to the kids and adults.