So, it's probably worth knowing that PowerShell CORE is what's cross-platform, not "all" PowerShell. And PowerShell is separate from, say, CIM/WMI/OMI. It's also worth pointing out that PowerShell is intended to act as a kind of a wrapper around whatever the OS does natively – not necessarily replace what the OS does natively.
So let's so you're on Linux. You can't use Get-WmiObject, obviously. However, if your Linux has OMI installed, you could maybe use Get-CimInstance. If your distro implements the CIM_OperatingSystem class, for example, that would tell you.