How do I actually find work in the US if I plan to do so?

Big 4 would usually have internal openings to allow employees to work overseas. Not sure if it is only available to good performing employees only or everyone. Check with your HR.

Working in US usually require a company sponsor. Next best alternative is to keep a look out for job opening in the US that might require Asia exposure/experience, or maybe even with US companies with presence in Singapore. You gotta start somewhere and slowly find your way through.

If u r working in big 4 accounting firm, u should have many opportunities to transfer to US via internal opening. U should approach yr HR.
I was offered a position in US by my company many years ago and the salary really attractive compare to Sg even after tax.