I found that after doing IF for a few months, I had WAY more energy in the morning than I used to.
I used to be groggy from the time I woke up until like noon, despite getting 8 hours of sleep, and REALLY depended on caffeine in the morning.
now I’m good to go right after waking up, and I’ve even switched to drinking decaf.
In any case, I’d recommend drinking black coffee over any kind of zero calorie drinks for caffeine.
Regarding morning time constraints, just get a keurig lol