I wore sarongs a bit before I started wearing kilts.

They are certainly unisex, although apparently in Indonesia the men's sarongs are chequered and the patterns represent the wearer's house. Sound much like clan tartans? The women seem to get to wear any colourful pattern they fancy.

However, in the West any design goes on sarongs for either gender. Sarongs with celtic knot patterns are readily available, and I have worn them, even though I doubt that they resemble anything worn by our celtic forebears.

I was forever tripping over the hem of my sarong, so that I was always shortening them, or rather tearing off the damaged part, LOL! Maybe that's because they were all one size and I am a bit vertically challenged. Knee length is more my style, as even if a kilt may look long on me to some, at least I can't trip over it!

As for the heat, you can get kilts in light weights and in cooler fabrics, or just with fewer pleats if you don't like those options.

There's also the issue of a sarong being a non-tailored garment, and so automatically informal. I have only once even seen a woman wear a sarong on a city street, and never a man, and I think that's the reason, although I'm sure you would see this in parts of Asia.