I believe GAHH is owned by World now. I found their 50’s and 60’s kits work very well. The earlier ones from the 30’s are hit or miss.

https://gahh.com/

https://www.worlduph.com/

I cut clear plexy strips 1/4" - 2" every 1/8" in size 48" long. (A few are set to 1/16" dimensions.) I find many uses for them. They save a lot of time making beading and binding the correct size.

Is the leather very firm and almost crunchy where it turned white? I have had that happen to me before where I have heated the leather too hot and turned it white and crunchy.

How do you feel about it?
In my experience, it looks about right for a thin material with a large top thread and a thin bobbin thread.

Garret leather supplies the woven leather. It is very price over $700 per yard (or per foot I can not remember). I believe Singer gets their woven material from Spinneybeck leather

https://www.garrettleather.com/catalog/custom-services.html

https://www.spinneybeck.com/index.php?/shop/products/leather-weave-lw

Roje leathers sells aligator and other exotic materials.
I also have not worked with aligator but have worked with lizard and that is dificult because it's thin and does not stretch.

This is a sample piece for a customer. All the strips are 7/8 wide and hand woven together.