Mr Rick
The 4th picture shows endgrain capillaries which defy walnut.
Purpleheart has the same endgrain structure as Bubinga.
Face grain for walnut is rather open pored whereas Bubinga is more similar to Rosewood and purpleheart.
https://www.woodworkerssource.com/bubinga/bubinga-hardwood-sample-12x3x6.htmlBlack Walnut has a janka hardness about 1010 whereas Bubinga is 2400-2600, being more than twice as hard.
However, I’ve had Peruvian walnut from a guy doing gunstocks and it was much darker and more dense than American Black Walnut.
Irrespective of the wood used, it looks great and being square, all the better.