I used the Device 229 commands in my Pronto TSU9400, except I used the following Device 238 commands since they weren't available under Device 229: Menu, Video Resolution, Play_Pause.
Some comments:
1. The Menu command (Device 238) doesn't work for me. It doesn't do anything. I'm going from TSU9400->RFX9600->Xantech (optically)->Apple TV in case it matters. I haven't tried direct IR from TSU9400 to Apple TV yet.
2. Aside: Apple's latest 2021 remote (correctly) refers to the old "Menu" button as the back button (should have been called the back button years ago).
3. As Lyndel mentioned, I also haven't found any apps that use Channel Up/Down (I'm in US).
4. Device 229 Discrete pause doesn't work with all apps. For example, it doesn't work with Youtube TV.
5. Forward and Reverse also doesn't work with all apps. For greater reliability (so as to be consistent across all apps and minimize confusion with users of the remote), I just use Cursor Left and Cursor Right, which also works as rewind and forward even from a playing state.
6. I taught my Apple TV commands from an old unused Dune remote. The learned discrete pause (and discrete play) button works in the apps that I tried (including Youtube TV). For some strange reason, the device 229 discrete pause button works with some of my apps but not in other apps (like Youtube TV). However, the learned pause button works in all the apps that I've tried.
7. Note that the following commands can be taught to the Apple TV (these are not available in the Device 229 commands provided above): Next and Prev (behaves like Track -/+, IIRC with Music app), Stop. Granted, these buttons don't see to be that commonly used.
Anyway, I use a combination of the Device 229 and Dune commands that I taught my Apple TV. I especially love the discrete power on and off commands that Lyndel provided, as well as the control center command (apparently, you can also teach the Apple TV a control center command, but it won't work unless you also give it a 1 sec duration). I actually find it useful to have a control center button, since I have HomeKit automation that I can access more easily.
