I don’t know of any stainless steel kayak carts. All of the ones I’ve seen are either aluminum or plastic some with stainless steel hardware. Stainless steel for the body of the cart would be overkill, heavy and expensive.
I have a 20 year old WheelEEZ® cart that is aluminum with pneumatic tires and plastic hubs. There are a number of other manufacturers with identical looking, but much less expensive carts available in stores and online. Still looks pretty much like the day i bought it in spite of extensive use in salt water environments. Broken down it fits in the hatch of my boat.
My cart does not look anything like the one you had, but will work for and canoe or kayak.
I have this same kayak cart as yours and the one shown. It works great for my 14’7” canoe. The trick is figuring the best way to strap it on and get it centered. I made 4 short loops out of rope attached at the top corners and then I don’t have to fiddle around underneath trying to figure out what is what to connect to. I then use two cam straps with hooks on the end. Mine came with one loop cam strap 10” long and it worked but I think 2 straps is better.
You did almost the same thing I did except I made rope extenders off the 4 corners that put the loops above the gunwales of the canoe then I just connect the hooks on the ends of the cam straps and pull tight.
I found on my canoe with a flat oil can bottom and a bumpy path the kayak cart was oil canning the bottom a lot. I just put a foam block between my center seat and the hull floor and that’s where I attach the cart now. Boy did that make a nice difference.