selectf.ps1

Import-Module PSStringScanner

function selectf {

    $ss = New-PSStringScanner ($args -join ' ')
    $select = $ss.scanUntil("(?=from )")
    $null=$ss.scan("from ")
    
    if($ss.check(" where ")) {
        $targetPath = $ss.scanuntil("(?=where )")
        $null=$ss.scan("where ")
        
        $whereVar = $ss.scanuntil("(?==~ )")
        $null=$ss.scan("=~ ")
        $whereValue = $ss.scan(".*")
    } else {
        $targetPath = $ss.scan(".*")
    }
    
    $cmd = "dir {0} | select {1}" -f $targetPath, $select

    if($whereVar) {
        $cmd += ' | where {{ $_.{0} -match {1} }}' -f $whereVar, $whereValue
    }
  
    $cmd | iex
}

#selectf "name,ext*,length from 'C:\temp'"
selectf "name,ext*,length from 'C:\temp' where extension =~ 'png$'" # use a regex

Prints

Name                         Extension  Length
----                         ---------  ------
acn.png                      .png      2089337
adam.png                     .png       126697
amazon.png                   .png        55226
AnamorphicArt.png            .png      1249449
arvixe.png                   .png        17622
AWS+PS.png                   .png        13853
aws.png                      .png       330830
awsX.png                     .png      1000262
BadAnalogyGuy.png            .png       140200
bdd.png                      .png        99822
BeautifulReports.png         .png       220837
BestPractices.png            .png      1389105
beTheSquirrel.png            .png      1248603
blank.png                    .png         2775