OK, so you want more retirement income, got it. What's wrong with increasing your CPF Retirement Account balances? That would increase your monthly retirement income, and it would do so better (more "bang for the buck" than all of the other options mentioned so far). You're well below the maximum Retirement Account balances allowed.
You can add any amount(s) you like, up to the current Enhanced Retirement Sum (counting principal only; interest can accrue above the ERS). Every time the ERS is raised you can do more. You can even do "cross-spouse" transfers if you want, i.e. your spouse transfers his/her OA dollars into your RA and vice versa. And you have no insurance carrier default risk, only the risk the Government of Singapore defaults -- a very low risk indeed.