Ends in 3 chapters?? Since when! I'll be sad to see this one go, but hopefully it allows Nanashi the freedom to try a whole new venture.
I have read far too much brainrot catgirl manga that I probably take it for granted everyone knows what nyaa/nyan means. Fun fact, "wan" is woof!
The cat's name is Gomanosuke (胡麻の助), and I think you're right about the origin. :) The full page shows them calling him this in context.