Debian Stable, in my experience, can stay online for months, even over a year, with very little attention, and still work as well as you left it. You can also install RHEL or a rebuild, like AlmaLinux, RockyLinux, or Oracle Linux, as a workstation distro.
As for the device, my use case is fairly different so I’m not sure what to suggest. Maybe an Intel NUC, or a Framework laptop.