First, you need to install Clipt both on your mobile device and your Android TV device. After that you need to give permission inside the app to access your Google Drive, which will be used as the way of transmission between your devices.
After installing Clipt, you need to install Buttons Mapper on the Android TV. Enable access to the Accessbility Service on Android TV which will be used to identify the keys you press on the remote controller. The application is donation-ware, but the way it is made its conceivers well deserve their bucks. You have to "remap" one key, which instead of being used for their default action, will be used to trigger the "Paste" event in Android, since from all the TV remote apps I tried out, no one had a paste button for that action. In my case, I used the Netflix button which I don’t use to trigger the Paste action.
This way, I can select and copy long pressing the desired text on the source Android device, use Clipt to trigger Send to Remote. The clip contents pasted into your Android TV appears in a short notice but in the end you hang to the text field in the app in your Android TV and once there, you’ll click the remapped key to trigger the paste button, and "Voila", you have your text pasted in your android TV !