stretches to target t-spine?

To start off, yes, I know that the t-spine does not move much and that a lot of mobility comes from the shoulders, lower spine, and even hips. That said, mine is basically straight. I feel like I should be able to get a little more openness there. However, whenever I do backbend stretches, I feel nothing there, or maybe a little on deep inhales. The stretch sensation tends to localize right below my sternum, in that triangle area before your ribcage completely ends. Depending on the stretch, I can also get a stretch throughout my abs and related muscles. But never the t-spine. I've tried laying across a foam roller or yoga block, with it directly under the middle of my spine, and my arms over my head to add more weight. This seems like it should target the t-spine, but it just gets that sternum/upper abs area. Any recommendations?