Unfavorably. There is no US-Singapore income tax treaty and CPF is not a qualified plan under US law, so employer CPF contributions are generally taxable compensation when made. The treatment of interest credited inside CPF is less settled: under the employees'-trust analysis (IRC section 402(b)), earnings are often deferred until distribution for rank-and-file employees, while other readings tax them annually, and preparer positions vary. The Foreign Earned Income Exclusion can absorb contribution income within its cap.
What is not debatable: CPF balances count toward the FBAR $10,000 aggregate and Form 8938 thresholds. Singapore also has no totalization agreement, which separately exposes the self-employed to full US self-employment tax.