視覚的に確認

1) Windowsキー + Rキーを押して、ファイル名を指定して実行のウィンドウを表示
2) winverと入力してOK

PowerShell で 取得

20H2よりも前か、 20H2 (以降)か でやり方がちょっと異なります。
## Windows 10 20H2 よりも前

 $CurrentVersion = Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion"
"Version " + $CurrentVersion.ReleaseId + " (OS Build " + $CurrentVersion.CurrentBuild + "." + $CurrentVersion.UBR + ")"

結果

Version 2009 (OS Build 19045.3803)

## Windows 10 20H2 よりも前

 $CurrentVersion = Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion"
"Version " + $CurrentVersion.DisplayVersion + " (OS Build " + $CurrentVersion.CurrentBuild + "." + $CurrentVersion.UBR + ")"

またはワンライナーに（セミコロンで区切っているだけ）

$CurrentVersion = Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion"; "Version " + $CurrentVersion.DisplayVersion + " (OS Build " + $CurrentVersion.CurrentBuild + "." + $CurrentVersion.UBR + ")"

結果

Version 22H2 (OS Build 19045.3803)

両方まとめると

$CurrentVersion = Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion"
if ($CurrentVersion.DisplayVersion -ne $null) { $DispVersion = $CurrentVersion.DisplayVersion } else { $DispVersion = $CurrentVersion.ReleaseId }
"Version " + $DispVersion + " (OS Build " + $CurrentVersion.CurrentBuild + "." + $CurrentVersion.UBR + ")"

結果

Version 22H2 (OS Build 19045.3803)