How can I tap on the Revolut fx rates for trading overseas stocks?

You are better off having an Interactive Brokers send your SGD to them (they have a local Citibank account to accept FAST transfer via our SG bank accounts), then use their forex to exchange for USD, EUR, JPY etc.

They are a professional broker for stocks, options, futures, etc. The forex rate is waaaay better than any stockbrokers I have seen and even better than a similar Revolut competitor I checked out a few weeks ago.

Most importantly, the convenience of the SGD from an SG account to a local bank account, and using their platform to change to USD.

Just do a google search for Interactive broker how to transfer SGD