Whicj oparating system distribution for hosting a Bitcoin Core node do you recommend (e.g. Debian GNU/Linux, Tails, NixOS, MacOS)?
Tails isn't an option since it meant to be live OS while MacOS server has been discontinued[1].
[1]
https://support.apple.com/en-us/HT208312You can run Bitcoin Core on macOS by itself, but indeed, Apple doesn't make any servers, so the only way it makes sense to leave a node running on a mac 24/7 is if it's a desktop.
This means you can get more support if you experience some issues while running a full node.
Aside support, Linux is completely open source, unlike some other operating system like Windows and MaxOS which are not open source or open source completely. According to what people are posting on this forum, truly Ubuntu will be the better one to go for.
You can even use Livepatch (for free) to automatically patch the Linux kernel while its running, without reboots:
https://ubuntu.com/security/livepatchBut I think that there needs to be some kind of service for automatically downloading and updating your node. It can be a 3rd-party program or something, but I think one hurdle to that would be if Bitcoin core has any callback "configurable shell command" that it can run when Core is about to shut down, similar to the blocknotify event.