Many "smart" devices are sold with the idea that you can control your home from somewhere else. Maybe change the temperature on your way home or get notified when someone rings your doorbell. All this stuff requires servers to work.
Controlling some lightbulbs via bluetooth/wifi would be possible of course, but probably not very interesting for many.
Even a raspberry pi can run linux with an lxd desktop, and this i3 is a few times faster than a raspberry pi. But it depends on what you want to with it...
The performance target of "linux desktop running lxd" and the price tag "not crazy expensive" is not very clear...
I would personally look for a fanless barebone pc and equip it with as much RAM and storage as you like. One example for this could be the Zotac ZBOX CI629, which you can get for around 400 Euros and has a 13th gen Intel i3 built in.
Is this within your budget?
Thomas asked what would happen if everyone would jump, not how humanity would go on if all mankind is teleported to Rhode island. Still a funny video.
Now that was really a great answer to a question nobody asked.
Same for me. I was wondering if there is another difficulty or so
Not OP, but generally, you want to separate internal and external services as much as possible. Some even suggest running external services on a cloud server and internal servers on your LAN.
If you run internal and external services on the same host, you need to be careful to not make any configuration mistakes. Take extra time to also test what should NOT be possible.
We had it at work, but I never did anything else than receiving and resolving alerts. But it looked good for me and I liked the system.
While I really like uptime kuma, it seems a bit too restricted for OPs use case. For example, to monitor disk or CPU usage, you would need to write your own scripts. It would be doable, but not very nice.
At least how I understood the.question, OP would probably look for something like icinga.
With 4 TB, the price difference is quite painful (at least for me). With anything below, I'd buy an SSD without thinking twice.
Have you tried the official Nextcloud desktop app?