You may want to try here.
It is the official government website for applications for a (digital) vaccination certificate.
It is currently only operative for international travelers (including OFW's), and only if you travel within 14 days, but it might be your best bet.
I am not aware that for domestic travel you would need such a digital vaccination certificate. The vaccination card issued by your LGU when you got vaccinated should suffice for that.


Informative x 2