This file can be saved as .ps1 or .cmd and works for both. Even supports cmdline arguments!

universal.ps1.cmd

@(echo off) > $null 
if #ftw NEQ '' goto :init
($true){ $Error.clear(); }

# unpack arguments if they came from CMD
$hash=@{}; 
get-item env:argz* |% { $hash[$_.name] = $_.value }
if ($hash.count -gt 0) { 
  $args=for ($i=0; $i -lt $hash.count;$i++) { $hash["ARGZ[$i]"] } 
}

# powershell script starts here 

write-host -nonewline "There are ($($args.count)) arguments: "
$args |% {  write-host -nonewline -fore cyan "$_ ," }
write-host ""

return 
# powershell script ends here
<# 
:set 
set ARGZ[%i%]=%1&set /a i+=1 & goto :eof

:unset 
set %1=& goto :eof

:init
if exist $null erase $null 

:: add the cmdline args to the environment so powershell can use them
set /a i=0 & for %%a in (%*) do call :set %%a 

:: find the pwsh/powershell.exe
set POWERSHELL_EXE=
for %%i in (pwsh.exe powershell.exe) do (
  if EXIST "%%~$PATH:i" set POWERSHELL_EXE=%%~$PATH:i & goto :gotpwsh
)
:gotpwsh

:: Run this file as a powershell script
%POWERSHELL_EXE% -noprofile -executionpolicy unrestricted -command "iex (get-content %~dfp0 -raw)#" 
set _EXITCODE=%ERRORLEVEL%

:: clear out the argz
@for /f "delims==" %%_ in ('set ^|  findstr -i argz') do call :unset %%_

:: we're done
exit /b _EXITCODE
goto :eof
#>