Think picks and shovels. (1)
If you believe bubble tea will be a big seller in your town, find a manufacturer of the tapioca balls and other ingredients and approach them about being an importer of their product. Go to existing tea shops and Asian restaurants and markets and see if you can persuade them to carry your line of goods/sell bubble tea using your products.
I don't know if there are machines involved in making the product at the consumer level but you can purchase and lease the machines to your retail store customers. There's lots of different ways to make money off of bubble tea. Opening a new, dedicated establishment is the least desirable one.
(1) Investopedia: A strategy where investments are made in companies that are providers of necessary equipment for an industry, rather than in the industry's end product. A pick-and-shovel play, in practice, could be within the oil industry; an investor would purchase stock in a company that manufactures seismic data equipment that exploration and production (E&P) companies need to find new oil and gas deposits, rather than on the E&P company itself.
The expression may have been derived from the California gold rush, where many of those who profited did so by providing the miners with picks, shovels and other equipment needed for gold mining. The idea behind pick-and-shovel plays is that, in the case of E&Ps, for example, it doesn't matter if the E&P Company finds oil and gas or not, they will need to purchase specialized equipment either way.