Installing smart switch that needs a neutral wire without a neutral wire
While the Philippines have some unusual power configurations, none of that has any bearing here. OP has the modified Euro style hookup, where ground is centered halfway between the live conductors, 120V from either conductor.  Pick either supply wire to act as "neutral" here, just be consistent.

This is a switch loop.  What makes it special is it's a 3-wire switch loop because it controls two appliances, just as OP says. But it still has all the normal properties of a switch loop.

Including the absence of a neutral and thus, inability to power powered switches such as smart switches.  

OP's options are:


if it's conduit,  just fish another wire to be the opposite leg.  
Replace the cable to the switch with /4 cable, which has 4 wires and ground. /3 will not do, do not use a ground wire for a neutral especially not in the Philippines.  
Make both appliances switch together, freeing up the needed wire.
Find smart devices able to power themselves old-school by leaking small amounts of power through the load.  
Find a smart device able to live up in the ceiling rose, and be remotely controlled in some way.
Give up the project.