JSFiddle - React, Tailwind, and code Playground

HTML

<select id="myCombo" name="example">
</select>

JavaScript

// Creating the Structure you already got
var viewScope = {
	myTest: []
}
viewScope.myTest.push(["row1col1", "row1col2", "row1col3"]);
viewScope.myTest.push(["row2col1", "row2col2", "row2col3"]);
viewScope.myTest.push(["row3col1", "row3col2", "row3col3"]);

// Get the Combobox by ID
var myCombobox = document.getElementById("myCombo");

// Iterate through all options of myTest
for (var i in viewScope.myTest)
{ 
    // Create a new Option for the Select
    var option = document.createElement("option");
    // Add the 3rd Columns as Text
    option.text = viewScope.myTest[i][2];
    // Add the Option to the Select
    myCombobox.add(option);
}