Look of a refurbished thinclient with a 6th or 7th gen Intel CPU with the "T" at the end (for example i5 6500T). Those are basically power optimized mobile CPUs for desktop PCs. Those are currently best value for money IMHO.

Alternatively use an old laptop, which is great for beginners, but storage extension will be very limited.

If all you want is Nextcloud, you are probably better off getting a managed service like this: https://www.hetzner.com/storage/storage-share/

Ice storage?

Cockpit is a simpler choice for that.

That is why I said it depends. There are many places where electricity cuts for a short duration are quite frequent. Often you don't even notice it, but a 24/7 server would be effected.

In general, I think the risk of laptop batteries catching fire is overstated especially if you limit the charge to 80% or so. So weighting these two issues against each other you can come out either way, but I think for most places it will come down towards a UPS being nice to have.

Depends. Usually it is still good as a UPS for a few minutes, and some laptops have a bios option to limit full charge which lowers the risk even further.

While your post does mention notifications which really helps with engagement and was lacking from most forums, the main issue was IMHO lack of good mobile support of all the main forum platforms until as you said Discourse came along, but by then it was too late.

Since Snikket is just an XMPP server, it can be used with desktop apps like Dino as well.

All the corporate gamification feature are probably quite annoying.

It really is an enterprise solution and I doubt your family will be happy with it.

Why not just set up a Snikket server and use that? You can easily create group-chats and share pictures and videos there and the interface is similar to WhatsApp.

Maybe https://picocms.org/

But Hugo is fine, no need to use all the advanced features.

Works great with Akkoma as well.

It has pretty much stagnated in the English speaking part of the internet, and only saw a huge boost in popularity in Brazil recently (due to Twitter being newly banned there).