Addons

Is there an app for TS5 that supports HID usb devices like there is in TS3? If so, where do you get it from?

First of all, there are no official Addons for TeamSpeak 5 yet.

There is an unofficial plugin installer there, but I don’t think this will help your solution.
[Plugins] Now available TEAMSPEAK 5 UNOFFICIAL Plugin Installer - TeamSpeak Client / Extensions - TeamSpeak

If you are talking about Remote Apps you can easily code yourself what you want, a Guide is linked below.

TeamSpeak Remote Apps - TeamSpeak Client - TeamSpeak

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