As the page has finished loading there's no way to retroactively get the Geolocation data direct within the screen, instead your best bet would be to issue a separate AJAX request to send the information you need to another PHP page, one built to accept the information.
let parts = data.results[0].address_components;
fetch('/path/to/page.php', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(parts)
})
.then(result => console.log('Sent to the other PHP page!'));
parts.forEach(part => {
if (part.types.includes("postal_code")) {
document.body.insertAdjacentHTML(
"beforeend",
`<p>PostalCode: ${part.long_name}</p>`
);
}
});