What are some suggestions on bank accounts and credit cards (or ones that link like UOB One and DBS Multiplier) for employees who don't get to have their salary credited under GIRO at all (requested from HR as well but that option is not available)?

Since it's unavailable, that means you're such with the few savings account with low interest rates. Thus, I'd recommend you to make use of CIMB FastSaver which offers 1% interest, no other conditions other than maintaining at least $1k. It allows you to make immediate transfers via FAST for free so you don't have to worry about your money being stuck in that account

CIMB FastSaver. 1% interest.

Cimb fastsaver for 1% interest. Look up on seedly reviews on this savings account. Alternatively, you can look at maxigain.

1. Put the money into a Citi maxi gain account
2. UOB one account
3. CIMB as the others have suggested

At the extremely level change a job but this would also give you a pay increase