Currently DCA $1k/month on Stashaway at 30% risk. Am considering to swap out of Stashaway and DCA $1k/month to VOO via TD Ameritrade instead. Long term investor. Advice?

Excellent way you are on.

Yes, TD Ameritrade Singpore branch account, currently the best alternative with zero U.S. equity trading fees.

VOO is excellent choice, surely formally underdiversified, but principal world market.

Try to consider MSCI World (not necessarily ACWI), and try to consider to mix in some China, f.ex. MCHI or PGJ, or if not risk averse some or all of these for a smaller proportion:

CQQQ, KWEB, KURE (later when listed ETF KSTR and an Hang Seng Tech Index ETF when listed).

Ireland listed ETFs have better dividend tax treatment, so with high yielding stock ETFs (like S&P500 ETFs around 2% per year) and these taxes recuring every year (or quarterly factually) it is better longterm-wise to have a cheap online broker that allows trading on the European markets, f.ex. tickers VUSA, VUSD, CSPX etc.

good luck !​​​