A lot of PM requests. I think it would be better for me to hint at the place that I frequent. The watch shop that I know sells a variety leather straps is the one at Pr*ngin Mall, next to the Sushi King. It's on the ground floor facing the traffic underpass.
The straps are not Hirsch or anything fancy. But they looked good and in a variety of colors (standard stuff - up to 20mm, 22mm at best but I didn't check). Calf skin alligator prints among the selection. They are stamped "made in Austria", I asked if that was true, the reply was, "everything is made in China now".

So that's all there is to it.

Caveat emptor, don't expect too much.
The shop does not display them, you need to ask.