GT86 2017 Daytime Running Light (DRL)
 

I have just sourced a 2017 GT86 from Japan and read about DRL being illegal there 🤷*♂️

I took a look at the engine compartment fuse box and the DRL relay is missing so is the socket. Wondering if anyone able to hook back up the oem headlight's drl to the car's drl system.

DRL are not illegal in Japan, simply they are not mandatory.
The DRL function is hard coded into BCM software, so you need to change it to an EU model, or you can buy a DRL kit from Japan. There are various types, the cheapest is a small harness that feeds the DRL sourcing the power from the headlights height motor.
If you need it, I have a 2019 BCM module for sale, but I'm located in Italy...

I see. Does this mean there isn't an easy way to get the DRL system installed? Reading from the car's manual, theres like a feature where the DRL only lights up when the stalk is on 'Off' or 'Auto" plus e-brake is released (for MT)

I think that's the behaviour of EU cars. I'm sure of the behaviours because I replaced my EU BCM with the JDM one to enable the theft alarm, and the DRL were gone.
The cheapest way is the harness you can find on Rakuten or Yahoo Auction.