Don’t even think about it
Here is a good link
If the tea is already sold in thailand it may already be registered for commodity coding and import taxes by the other importers.
Thai FDA and US FDA are similar and generally speaking if your item has an FDA in USA then the process of obtaining TFDA is a lot easier than if your item is not FDA US approved.
Seems like a lot of work for selling tea. The import tax might be high on that item also.