I need some illumination please. Not sure what manufacturer you are referring to.
As for the roux so many ways to make it, my Mom's and my normal is a low and slow no burn roux, the one mentioned on the first page is the fast and hot, most folks prefer making it.
Any oil and any thickener can be used including but not limited to okra, wheat flour, rice flour, corn flour and file. Any oil can and probably has been used at some point. Suet to 'possum grease, although a high flash point oil is generally the most readily avaiable.
You bring up a steam kettle as in most commercial kitchens, most chefs in a commercial kitcken will bake off large roasters of roux at one time and then store in the reefer for up to a month. You can now buy in local grocery stores more than one brand of commercially made and canned rouxs in assorted colors. They are found online also.
Hope that helps. I am still not sure of what manufacturer you are looking for, remember I am an old coonazz and sometimes my thinker don't understand so well.