Don't Buy Apple 4K TV Unless You Own an iPhone or iPad or a Mac: Support Email/TOTP 2FA, Please!
I am a brave owner of an Apple 4K TV device. I want to issue a disclaimer. It is a dangerous ownership experience, so I advise you not to try it at home; go with other streaming devices instead. I created an Apple account online to use the Apple Music app on Android. When I signed up, I was never asked for a trusted phone number and secondary authentication was done via email. This worked fine until I tried to log in to my Apple TV 4K with my apple account.
So, when I tried to log in manually, as I don't own an iPad or iPhone, I received the following message: A message appeared saying that I must update my account by navigating to appleid.apple.com in order to continue.

So, I did that, but it asked for a trusted number for authentication instead of relying on my trusted email server, which had been working fine until now. It just did not work. After trying two phone numbers, it said, 'An unknown error has occurred'.

I called Apple Support, who asked me to log in to the account using my wife's iPad. We tried logging in 3–5 times in different applications, including the App Store, iCloud and Safari, but it didn't work.

Eventually, Apple throttled my account so much that I could not add any phone number at all.
I waited a night before trying again and was able to add one of my friends' numbers, as my own numbers were still not acceptable to Apple. Then, when I tried to log in to the Apple TV 4K device manually, it said, "Verification codes can’t be sent to this phone number at this time. Please try again later.'

After waiting a couple of hours, I was finally able to log in to account.apple.com and change the phone number to mine. However, when I tried again on Apple TV 4K, I received the same error message.
Currently, I periodically check account.apple.com for login. When it works, I run to the Apple TV 4K like Tom Cruise in the climax scenes of Mission Impossible movies, but sadly it gives me the same 'verification failed' error. When I try account.apple.com, it says the same thing there too.
The issue with text-based verification is that Apple asks for it everywhere: whether you access Apple Music or Apple TV on Android apps, on the website, on webOS apps, or anywhere else. This would obviously end up throttling the verification system, as you might have to enter the verification code ten times a day if you access it over the web. If I access Music or TV on my Debian system running Firefox, I might need to enter the code repeatedly for some reason.
If they supported email or popular TOTP-based authentication, this wouldn't be an issue. However, Apple believes that text-based authentication for 2FA is more secure.
Whether it is secure or not is up to you, the readers. It apparently isn't.
My Apple TV 4K is a paperweight. It's just sitting there
At the time of publishing this post, I haven't yet managed to log in to my Apple TV 4K device. However, I have learnt that you cannot use Apple TV 4K peacefully without owning an iPhone, iPad or Mac.
Furthermore, I cannot use my Apple Music or Apple TV subscriptions on any of my streaming devices, including those running webOS or Android TV OS. When I try, I am asked to go to link.apple.com, where the same text-based authentication debacle continues.
Currently, the only device on which I can use my Apple Music and Apple TV subscriptions is the Android phone I originally used to sign up for the account, as it only asked for email-based two-factor authentication on top of credentials.

Since registering a phone number for two-factor authentication (2FA) as a trusted phone number with my Apple account, things have gone downhill.
I wish Apple would either support secure 2FA using Android apps like Apple Music or Apple TV, or support standard TOTP authentication or email authentication.
Text-based two-factor authentication is not only insecure, but phone numbers are also prone to the issues I am facing.