I haven't really worked with lemongrass before so I just wanted to know if lemongrass essence tastes quite similar to lemon, and if I can make tea with it.
Lemongrass is quite a common ingredient in herbal teas. But it has a different taste to lemons. It is milder than lemon.
Lemongrass essence should be food quality and as such you can also use that in drinks, but it will require even more testing how much you want to add. It might be a good option for people who can for some reason not use lemons, but it will not be the most natural choice for everybody.
So yes, you can use it but it will result in a subtly different drink.