It seems like there were many people who asked if there was an aftermarket power lift gate over the years. Finally there is one.
Here is a video of it in action
YouTube
Here is the vendor. It still shows as preorder though. P/n 9101.
Power operated tailgate lift assisting system TL105 – Autoease
Who wants to be the guinea pig?
New video of someone he recently bought one with the foot sensor:
Cartrimhome is now selling it for $480
Free Shipping Electric tailgate modified tailgate automatic lifting Rear Door For TOYOTA 4RUNNER 2010-2019