Generally yes, on the contribution side: there is no US-Hong Kong income tax treaty and MPF is not a US-qualified plan, so employer contributions are generally taxable compensation to a US person when vested. The treatment of account earnings depends on the trust analysis: under IRC section 402(b), earnings are often deferred until distribution for rank-and-file employees, with annual taxation applying mainly to highly compensated employees; positions vary between preparers. Hong Kong taxing none of this leaves little Foreign Tax Credit either way.
MPF constituent funds you select are typically PFICs, which can add Form 8621 reporting. The accounts themselves are reportable on the FBAR once your aggregate foreign accounts exceed $10,000, and count toward Form 8938 thresholds.