How to setup Apple TV, iPad, and HomePad as HomeKit hubs?

There are a set of Apple devices in place worked as a HomeKit hub, some of the limitations enabling all of the available HomeKit features such as automation, streaming HomeKit cameras remotely, and much more. Thus it is to follow where how to set up an Apple TV, iPad, and HomePod as home hubs.

With an Apple support document, which needs a breakdown of devices is what which can handle is with various HomeKit features:

With features getting set-up of automation, changing user permissions, or streaming HomeKit-enabled cameras remotely, is where you need a HomePod, an Apple TV 4K or Apple TV (4th generation) with the latest version of tvOS, or an iPad which features latest iOS.

There is a control of HomeKit accessories remotely where one needs a HomePod 2, an Apple TV 4K, Apple TV (4th generation), Apple TV (3rd generation), or iPad.
The device thus, however, sets up as a home hub which must remain in your home, connected to your home Wi-Fi network, and powered on.

How to set up Apple TV, iPad, and HomePod as HomeKit hubs?

Apple TV
1. With a two-factor authentication, make sure your Apple ID is turned on.
2. Check your iOS device with Settings >> Your Name >> iCloud >>Keychain and hence make sure iCloud Keychain is on.
3. Sign in with your Apple ID under on your Apple TV where Settings >> Accounts >> iCloud automatically sets up as a HomeKit hub.

Also check the status of your Apple TV as a hub thus far in the Home app while tapping the Home Settings icon in the top left corner. Just to make a note as a last resort, 3rd gen. Apple TVs work only with using HomeKit remotely, which does not support automation.

iPad
1. Sign into your iCloud with Apple ID (Settings >> Your Name >> iCloud)
2. Make it clear that iCloud Keychain is turned on (Settings >> Your Name >> iCloud >> Keychain)
3. Under Settings >> Home, turn on Home Hub option

HomePod
1. Make HomePod as a set-up, automatically featured as HomeHub.
2. Double-check Apple ID you are using for iCloud on the iOS device set up as HomePod as your HomeKit.