What were the traditional dresses for Hindu men? Well, that has been evolving but historically speaking minimalistic

Most men either wore nothing on top except the sacred-thread, with a dhoti on the bottom or just a kaupina.

Sometimes a short tunic on top.

I think Adi Shankaracharya even composed a poem on the Kaupina. The Langot is essentially the modern version of it. It's worn by wrestlers now. Sometimes ascetics.

Pagadis were also common, worn on the head sometimes.

Most people are aware of the dhoti, which would be quite close to traditional wear now. As it was, back then

Wearing nothing on your upper body is traditional

In the Zoroastrian Achaemenid Empire, many Hindus would fight for the Iranians in the Persian conquest of greece. The Hindus were depicted wearing a dhoti on bottom, nothing on top

I can post more in detail about history of clothing in India if people want.