Indenticar e substituir valores hexadecimal para "cor"

hexColor.php

<?php  

/**
 *  Trocar valores hexadecimais por cor
 *  @param string text
 *  @return string
 *
 *  @author Kugi Haito
 */
function hexColor(string $text) {
	function getColorHex(string $text) {
	    $letter = "";
	    $colors = [];
	    $positions = "";
	    for($i=0; $i<strlen($text); $i++) {
		    if ($text[$i] == "#"){
		    	$positions .= $i . ",";
		    }
	    }
	    $p = explode(",", $positions);
	    array_pop($p);
	    foreach ($p as $key) {
		    for ($j=intval($key); $j < intval($key)+7; $j++) {
			    if ($text[$j] == "#" and $j > $key) {
			    	// blank
			    } else {
			    	$letter .= $text[$j];
			    }
		    }
		    array_push($colors, $letter);
		    $letter = "";
	    	
		}
		return $colors;
	}

	$s_color = [];
	foreach (getColorHex($text) as $color) {
		array_push($s_color, "</span><span style='color:". $color .";'>");
	}

	$textEdited = str_replace(
			array_values(getColorHex($text)),
			array_values($s_color),
			 $text
		) . "</span>";
	return $textEdited;
}

// exemplo de entrada, e utilização..
echo hexColor("#6bc609Olá #21b29cMundo!");