Is there no way to upgrade PowerShell to v5 or even v4?
Não
On a fully patched Windows Server 2008 SP2, I've upgraded Powershell 2 to 3.
Para instalar o PowerShell 4+, você deve instalar o Windows Management Framework 4.0 e o Windows Management Framework 4.0 ou o Windows Management Framework 5.1 não suporta o Windows Server 2008 SP2
Fonte:
WMF 4.0 can only be installed on the following operating systems.
Windows 7 with Service Pack 1
Windows Server 2008 R2 with Service Pack 1
Windows Server 2012
Quanto ao PowerShell Core, como inclui Microsoft.PowerShell.Management
, ele também não oferece suporte ao Windows Server 2008 SP2
PowerShell Core (aka PowerShell 6) is officially supported on the following platforms:
- Windows Server 2008 R2, 2012 R2, 2016
Fonte: PowerShell Core 6.0