This is collection of icons/logos for operating systems and various applications detected by Matomo's Device Detector except AFNetworking apps (need specific names). Expected use case: an audit page showing data on past user logins or current sessions.
While most icons are 100% "official" (at the time of addition), for some more obscure or old ones I can't guarantee that a proper icon is being used. In fact, for some of them icon/logo of respective owning company or avatar of original creator is used.
For format consistency's sake some icons may have been edited slightly:

• spacing added to make up perfect squares
• excessive spacing removed, but to still keep square ratio
• all icons with dimensions over 1200x1200 pixels were resized to 1200x1200 (I doubt that anyone would need larger versions for potential use cases)
• side-text removed, unless necessary for differentiation of the icon from similar yet unrelated ones or essential to the logo
• solid background removed (for transparency), unless it is part of the brand, or it otherwise deemed important to readability
• all icons were converted to lossless WebP format except for device/type, client/type, bot/category, which are in SVG (all taken from svgrepo) to allow adjusting their colors through CSS to suit the website's style, if needed
• names of the files for OS/2, GNU/Linux, MTK / Nucleus, Perl REST::Client, HTTP:Tiny, AUX were changed to OS2, GNULinux, MTK Nucleus, Perl RESTClient, HTTP Tiny, ＡＵＸ respectively due to special symbols

If desired, you can see all the icons from the collection on one page here.

Example of convenient use in PHP:

#Initialize device detector
$dd = (new \DeviceDetector\DeviceDetector($_SERVER['HTTP_USER_AGENT']));
$dd->parse();
#Get OS
$os = $dd->getOs();
#Get client
$client = $dd->getClient();
#Set OS and client icon if they exist
if (is_file('/img/devicedetector/client/os/'.$os['name'].'.webp')) {
    $os['icon'] = '/img/devicedetector/client/os/'.$os['name'].'.webp';
}
if (is_file('/img/devicedetector/client/'.$client['type'].'/'.$client['name'].'.webp')) {
    $client['icon'] = '/img/devicedetector/client/'.$client['type'].'/'.$client['name'].'.webp';
}

For a more elaborate use (audit page), check this php (for backend) and twig (for frontend) files.