Do you mean something like

In file "ifelse.ps1"

param(
[Parameter(Mandatory,Position=0)][switch]$test,
[Parameter(Mandatory,Position=1)][ScriptBlock]$ifTrue,
[Parameter(Mandatory,Position=2)][ScriptBlock]$ifFalse)

if ($test) { $ifTrue.Invoke() } else { $ifFalse.Invoke() }

Then in usage

PS> ./ifelse.ps1 $true { 'yes' } { 'no' }
yes
PS> ./ifelse.ps1 $false { 'yes' } { 'no' }
no

Or replacing my last line in the file with

$test ? $ifTrue.Invoke() : $ifFalse.Invoke()

That kind of thing?

I must admit I was thinking about PowerShell without the actual ternary operator, I prefer the type ScriptBlock to refer to some code.

Is your issue that passing around a function does not execute it? Think of it as a delegate, a script block or a callback. You are passing a reference to the function, not the result of it's execution.