I don't think your age is an issue, but moving to SG could be as it will be harder to get a job in a position you don't have a lot of experience in. :/

I think it'd be better to gain some experience in your home country first, but I understand it might not be possible.

I think your best bet would be to look for a DevOps position which would provide you with more opportunities for coding while valuing your sysadmin skillset.