Do I pay tax in the US or India?
Your investment in US Stocks is fully regulated. India and the U.S. have signed a Double Taxation Avoidance Agreement (DTAA).
This prevents Indian Residents from Double Taxation.
Any Capital gains on your US stocks investments are only taxed in India.
Upon creation of your US stocks 2 in 1 account, your broker will file a US tax compliance form called the W-8BEN form (Declaration) with your details and Nationality.
This form acknowledges that you are a foreign investor earning an income in U.S. & further allows you to take capital gains tax exemptions in the U.S. More info on taxation here
However, you will be responsible for paying either short- or long-term capital gains tax in India based on your investment horizon.