As I beginner, how many lots of VOO is sufficient? And should I invest in US Stock such as Tesla, Sq, Roku as well?

It hard to know VOO that is sufficient but is not impossible with dedication and research you can make it investing US stock is a speculation always research and understand before trying to invest

always remember invest in what you know and understand the basic before making any investment​​​

Tsla, sq , roku are high volatility. If u are ok with that why not. High volatility = high gain.

Percentage distribute depend on your ability to see your portfolio swing. If u wan swing less put more to VOO, swing more put more to tsla, sq, roku. (Voo is relativity less volatile, but still volatile.