Microsoft
Get logged-in users on a computer:
query user /server:$Computer
query user /server:$SERVER
interesting: https://adamtheautomator.com/how-to-get-the-current-user-logged-on-with-powershell-all-the-ways/
Get uptime:
Get-CimInstance -ClassName Win32_OperatingSystem | Select LastBootUpTime
Get-Uptime