Thank you for your insight. While I didn't state it, botulism is my
main concern. ...
Provided I maintain a good pH and pressure cook, would
that be sufficient?

Well... you can pressure can low pH food (drink) and be safe. You'd need
to try to find a pressure/time for your specific item. OTOH, if you
drop the pH down enough (like jelly, etc), then the "boiling water bath"
method can be used. It depends whether you trust your life to your pH
measurement method!

Note... pressure canning is going to raise the temperature up toward
240F and it is going to be held there for a time, say 15 - 20 minutes.
I really wonder how tea would taste after such treatment (most folks
usually simply steep tea in LESS THAN boiling water, right?).


I'm not a canner, so I'm learning on this front too. What would be the
best procedure for this?
....
I thought when you canned jars, air was
pushed out. What would happen if I pressure cooked capped bottles?

I've wondered this myself. You are correct that air is pushed out.
However, commercial canners seal the metal cans before they are pressure
cooked... so I suppose it might be doable with glass as well? If you do
it, let us know... It'd be interesting to use this method to can
things like juice, hot sauce, etc. in "beer" bottles.