As an ex local scholar who also did mechanical engineering. Go for the tech/finance route unless you enjoy pandering to the bosses. 6 years in
DSTA is almost irrelevant in the private sector and your other options is to go to another agency.
Starting salary is indeed high in the public sector, but after a few years you’ll wonder why you work harder than your finance/tech peers, but earn lesser. Also working for 6 years in public sector turns you into a yes man. If that’s your calling, go for it. Otherwise stay far far away