1.php

<?php

function do_a_thing(string $firstVar, string $secondVar){}

$items = [
    'mouse'      => 'some arbitrary value',
    'keyboard'   => 'some arbitrary value',
    'monitor'    => 'some arbitrary value',
    'microphone' => 'some arbitrary value',
    'headset'    => 'some arbitrary value',
    'PC'         => 'some arbitrary value',
    'webcam'     => 'some arbitrary value',
    'desk'       => 'some arbitrary value',
    'pen'        => 'some arbitrary value',
    'post-it'    => 'some arbitrary value',
];

$limitValues = ['mouse', 'keyboard', 'monitor', 'microphone', 'headset'];

foreach ($items as $key => $value) {
    if (array_keys($limitValues, $key)) {
        do_a_thing($key, $value);
    }
}

2.php

<?php

function do_a_thing(string $firstVar, string $secondVar){}

$items = [
    'mouse'      => 'some arbitrary value',
    'keyboard'   => 'some arbitrary value',
    'monitor'    => 'some arbitrary value',
    'microphone' => 'some arbitrary value',
    'headset'    => 'some arbitrary value',
    'PC'         => 'some arbitrary value',
    'webcam'     => 'some arbitrary value',
    'desk'       => 'some arbitrary value',
    'pen'        => 'some arbitrary value',
    'post-it'    => 'some arbitrary value',
];

foreach ($items as $key => $value) {
    switch ($key) {
        case 'mouse':
        case 'keyboard':
        case 'monitor':
        case 'microphone':
        case 'headset':
            do_a_thing($key, $value);
        break;
    }
}