OK, routers. My use is not to cut the dado, but to clean up a dado, finish a stop dado, hinge mortice etc. So, light duty use. I think the small size simple ones would do for dados, but I wonder if the large base is better for cleaning out hinge mortices.
My first inclination is just a small bent neck chisel, but of course, no depth stop.
L-N and Veritas "small" are out of stock. Large are overkill I believe.
The Cowryman is an interesting tool. For one thing, the blade is like a chisel in you can pull it out and sharpen conventionally, but it is not a "foot" . Basically a chisel in a holder.
Like a lot of tools, most are out of stock.