Just sharing how I do it:
Install Android TV remote on my phone: https://play.google.com/store/apps/details?id=com.google.android.tv.remote&hl=en
Then if I need to paste something, I just use my phone instead of the remote. It's a lot easier to use a phone keyboard as well.
For example if I have an email with the portal URL, then open the email on the phone, copy it, switch to remote, and paste.