How can I merge every 2 arrays into 1 and append to new array (outside of loop) in foreach loop?

I have a result from an sql query:

 array(4) {
[0]=>
array(8) {
["question_category"]=>
string(11) "Engagement"
[0]=>
string(11) "Engagement"
["result"]=>
string(6) "6.6667"
[1]=>
string(6) "6.6667"
["employee_first_name"]=>
string(5) "Person A"
[3]=>
string(5) "Person A"
}
[1]=>
array(8) {
["question_category"]=>
string(9) "Tenure"
[0]=>
string(9) "Tenure"
["result"]=>
string(6) "7.6667"
[1]=>
string(6) "7.6667"
["employee_first_name"]=>
string(5) "Person A"
[3]=>
string(5) "Person A"
}
[2]=>
array(8) {
["question_category"]=>
string(11) "Engagement"
[0]=>
string(11) "Engagement"
["result"]=>
string(6) "7.6667"
[1]=>
string(6) "7.6667"
["employee_first_name"]=>
string(6) "Person B"
[3]=>
string(6) "Person B"
}
[3]=>
array(8) {
["question_category"]=>
string(9) "Tenure"
[0]=>
string(9) "Tenure"
["result"]=>
string(6) "8.3333"
[1]=>
string(6) "8.3333"
["employee_first_name"]=>
string(6) "Person B"
[3]=>
string(6) "Person B"
}
}

And I want to end up with a results array:

$results = array(['x' => 6.6667, 'y' => 7.6667],['x' => 7.6667, 'y' => 8.3333]);

With 'x' being this 'result':

string(11) "Engagement"
["result"]=>
string(6) "6.6667"

and 'y' being this 'result':

string(9) "Tenure"
["result"]=>
string(6) "7.6667"

fyi... "result" is AVG('result') from DB GROUP BY question_category,...

I've been stuck on this for a while now, so I'd really appreciate some input!

As noted in the comments, I'd recommend solving this in SQL. But if for whatever reason you can't, just group by employee name, and map the question category to x or y as needed.

$data = [
    [
        'question_category' => 'Engagement',
        'result' => '6.6667',
        'employee_first_name' => 'Person A',
    ],
    [
        'question_category' => 'Tenure',
        'result' => '7.6667',
        'employee_first_name' => 'Person A',
    ],
    [
        'question_category' => 'Engagement',
        'result' => '7.6667',
        'employee_first_name' => 'Person B',
    ],
    [
        'question_category' => 'Tenure',
        'result' => '8.3333',
        'employee_first_name' => 'Person B',
    ],
];

$grouped = [];
foreach($data as $row){
    // I think this is the mapping? If anything else exists,
    // this will throw
    $xOrY = match($row['question_category']){
        'Engagement' => 'x',
        'Tenure' => 'y',
    };
    
    // Group by name
    $grouped[$row['employee_first_name']][$xOrY] = $row['result'];
}

// Remove the names (optional)
$grouped = array_values($grouped);

var_dump($grouped);

Demo: https://3v4l.org/PN1t4#v8.2.7