System.Runtime.InteropServices.RuntimeInformation (class)

The FrameworkDescription property return the name of the .NET installation on which an app is running, thus the following PowerShell command returns the .NET framework version on which the current PowerShell was built on:

PS C:\> [System.Runtime.InteropServices.RuntimeInformation]::FrameworkDescription
.NET 9.0.1

As per this Stackoverflow answer, the previous command does not work with PSReadLine version 2.0.

Compare with

• the value of Value under the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full.
• [System.Environment]::Version