You guys are funny. You talk as if you know something but this comment is so ignorant. Sorry i call a spade a spade. Unlocked bootloader means you wont get any updates forget about seeing registration for beta. Your knox will be tripped. Please dont talk if you dont know what you are talking about. Do you even know what a bootloader is ?
The correct term is Sim-Unlocked variants.
You and me are same unlocked on t-mobile. As of now other than waiting for banner to show up in members app there is no solution (If there is one it cant be discussed on this forum) as that would be little more technical. That too will work only if some tech savvy user gets the update. So far as much as i know no one in US has seen the banner (Note 20/Note 20 Ultra) and hence no one has been able to get it. There is plenty of Articles those are just click baits or people trying too hard to be the first ones to report it. I called out plenty of such articles from many android sites and asked the authors to share screenshots or give one example of someone who got it. They all chicken out so dont believe fake news.
In short lets wait for the banner to show up and hpe whatever Samsung needs to fix for the banner to show up is fixed as soon as possible.