You would need to hook up the Hopper to a Dish satellite signal in order to get the guide info for the OTA channels. (You would also need to keep the Hopper hooked up to the satellite signal in order to get software updates for the other features you are asking about.) Without the guide info, the Hopper cannot be used for OTA. With the guide info and a satellite signal, a deactivated Hopper can be used for OTA channels and built-in apps such as YouTube. I have a deactivated purchased Hopper 3 that I use precisely that way. However, even if the Hopper is activated, any Joeys that are not activated for Dish service will not even connect to the Hopper for apps or any other functionality, if I remember correctly.
Yes, HWS supports YouTube. I don't remember exactly when it was added, but it has been there quite a long while. It was much more recently than the switch to the Carbon UI, though. So, simply having the Carbon UI does not guarantee that the receiver will have YouTube on it. Also, as has been mentioned, media share was completely removed back at the end of 2020.
If you do not have a Dish satellite dish that you can use for hooking up the Hopper(s) to a satellite signal, I happen to have a spare dish, along with the Solo Node(s) that I am not currently using, that I could send you. Send me a private message if you are interested.