Have you guys tried coconut water?
I added some passion fruit sugarfree lemonade to it and it became an amazing drink with some vodka.

What are some weight exercises for thoracic spine mobility as well as core?

Apart from some of these stretches, I am doing a form of punching exercise where i take a cable and stand at a slight angle facing away from it, do a slow punch and twist body, extending scapula further away from the machine.
It feels so good for my spine.

I also do back extensions, not quite there yet to do sidebends on it, scary shit.