Believe these were JDM mirrors. A few years back I bought a set of aftermarket mirrors that look like these. A member in Canada was selling them. Arms are chrome and mirror head were black. For the price were a pretty good deal.
Yes those are JDM. They exist on many vehicles in Japan. Even a new 200 series will have a much smaller version on this if it’s a JDM truck. However the off-road crowd will remove them prior to hitting the trail as they will get torn off.
I read the reason for these fender mirrors the streets in parts of Japan that wasn't room for mirrors to extend past the body.
Found the person I bought my mirrors from. User name on Mud @kash . He still on Mud. Got the wrong arms by mistake and replacements were mailed quickly. Still have to get the other arm back. Been an issue we a address to return in the US.