After doing a lot of research, I stumbled upon Malaysian car forums. Unfortunately, it's only available based on a car's variant. Otherwise, it requires major modifications in ECU, which is something I would not do. All hopes have been lost.
Alternates would be those no-name Android multimedia systems but I'm absolutely not a fan of those, as they completely ruin the interior's aesthetics, doesn't matter how many gizmos are slapped in it. Another I think of is installing an aftermarket camera for a front view if it's possible, and my last option would be blind spot mirrors which at least do the job based on my experience.
It seems like Yaris's seat is so low that it's hard to predict the surrounding space doesn't matter how skilled the driver is.