Tips: Can non-US citizens own them?
ETFs are available in most developed nations. In the US, anyone who can open a brokerage account and buy stocks will be able to buy them. Still there could be some limitation in some countries on trading US based ETFs. The easiest way to find out what ETFs are available in your region for trading is to contact your broker.
Naked options trading is very risky - many people lose money trading them. It is recommended contacting your broker or investment professional to find out about trading risk and margin requirements before getting involved into trading uncovered options.