[Fire TV Android Development] SweenWolf:
I don't personally use magisk, thats why its not included, as its a patch and not a ROM the choice is yours, but it does not require you to have Magisk installed, it will work either way.

Its actually was used for Enabling/Disabling Accessibility on the fly. If you don't know after flashing CLH you can use traditional apps for Home button mapping.

Use LaunchX or LauncherHijack or FireTVSettings Lite (I don't remember if I have published it to XDA or not) or the Full FireTVSettings (It has built in mouse function, which can be used instead of mouse toggle) can be invoked by long pressing "play/pause" button.

I may change the Long press to do some other thing but nothing is in the mind yet.

Yes, Check for Updates will always return it, thats why you can bypass OOBE system update (It will let you update your remote however).

It is intended. If you want to restore update checking function, just get a copy of original OTA apk and do a simple install in file manager, your OTA will be unpatched. Use at your own risk. Amazon can flash updates while in the system. TWRP will most likely prevent it but better be safe because its the job of kernel not the recovery.

Yes, you are right because its a system app it won't give you option to uninstall.

You can only open SettingsActivity only if the app is opened by a third party launcher. (Open a third party launcher, click on Custom Launcher your Settings Activity can be then invoked by Long pressing Menu Button)

It is by design. And it shouldn't show in Your Apps and Channels because is you are not using a third party launcher then whats the reason to show the app in there. It will only be visible in a third party launcher, alternatively [long press to invoke hud, go to custom launcher settings and then long press menu button]

Well If you had rebooted before patching the stock firmware it would have blown your efuse.

TWRP prevents unwanted updates but when booting you are not in twrp and you will have your TWRP removed and your stick will be patched, worst case scenario your stick will fail DM-Verity check and will be permanently bricked be no option of going back. You might have known not to flash any update to magisk while through the system (that basically means you shouldn't flash magisk other than TWRP itself) because this will rewrite your microloader (please read through the unlock guide of mantis)

This step is to make sure you don't accidentally brick your stick. Or read how an Android System Starts to get full knowledge about it.

There risk of a third party launcher is as same as without CLH patch, but they are visible to Amazon because of Alexa, which scans and creates hashes for each file installed.

Actually Under the Hud Amazon provides a way to the vender to change the launcher if needed and does give them option to hijack home button, you can also see this feature where home button press while playing game then it will stop you from opening Amazon Launcher

Its shouldn't be a big issue but it may be. It depends on the time investment and patching. So it can be patched on a rooted device certainly. But I cannot guarantee on a non rooted device.

I haven't checked or flashed 6.7.0.2 yet.

You are most welcome.