For private and public photo sharing with a 5000 character description limit and commenting there is Pixelfed. I use it as a private and public Instagram.
There is also Misskey which has internal non-federated groups on it's own instance, files and picture sharing. You could try-out if Misskey is something and self-host. It has mobile apps well.
You say you want something more private for friends and family, but fediverse is about connecting with the fediverse.. as I interpret your question you could use any social platform or forum software you want, it doesn't seem need to be fediverse enabled, is that right?
For private and public photo sharing with a 5000 character description limit and commenting there is Pixelfed. I use it as a private and public Instagram. There is also Misskey which has internal non-federated groups on it's own instance, files and picture sharing. You could try-out if Misskey is something and self-host. It has mobile apps well.
You say you want something more private for friends and family, but fediverse is about connecting with the fediverse.. as I interpret your question you could use any social platform or forum software you want, it doesn't seem need to be fediverse enabled, is that right?