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.

Collection also comes with a custom class \Simbiat\DDCIcons that can help get respective icon with support of variable images formats (with prioritization) and a fallback icon.
Functions available:

• getBot(string $bot, ?string $category = null)
• getBotCategory(string $category)
• getBrowser(string $browser, ?string $family = null, ?string $engine = null)
• getBrowserFamily(string $family)
• getBrowserEngine(string $engine)
• getOS(string $OS, ?string $family = null)
• getOSFamily(string $family)
• getClient(string $client, string $type)
• getClientType(string $type)
• getBrand(string $brand, ?string $type = null)
• getDeviceType(string $type)

Names of the functions should be self-explanatory, and all of them require at least the name of the respective entity. with getClient also requiring type of the client. Some of the functions also support optional arguments, that allow alternative fallback icons, if found.

Class has the following settings:

• string $basePath - base path to be attached to the returned value, which will complete the value to a usable URL for your website. Note, that you may need to use rewrite rules in the web server settings to actually make the files accessible, though.
• array $extensionPriority - priority of the file formats. If a folder has multiple versions of an icon the fist one existing will be used. Lower case is expected both in the array and in the actual files.
• array $namesToReplace - names that will need to be replaced due to file systems' limitation or for other reasons (if customized).
• array $paths - paths used by the class. Do not change, unless you know what you are doing.
• string $fallback - default fallback icon relative to $basePath. Same as with $basePath you may need to use rewrite rules in the web server settings to make it accessible for clients.

Note: while release versions are meant to match current release of DeviceDetector (with added datestamps to identify local changes between them), they may lag behind a little bit or not change, if new DeviceDetector release did not have new entities.