I need some opinion from the crowd.

To give a brief context, I graduated with a pre-experience Masters in local U with Dean's list. I read my postgrad in business. For undergrad, I read my bachelor's in SIT and hence am unsure if it's recognized as a private or local U. I did diploma in supply chain management.

I usually get called up for interviews but always fail to secure the job. I applied to economic development SBs such as MTI, STB, EDB, IE Sing, Spring and have always successfully pass through to the second/last round before getting rejected. My O level grades are sub-par and I think they're hiring on a similar SOP?
Any advice if I should continue applying to the public service or just aim private sector and if so, where should I aim?