A few years ago Dark Horse Comics released an introductory graphic novel for the ARMS series on Free Comic Book Day, part of a partnership with Nintendo. That was in 2018, and nothing was heard of it further.
Unfortunately, the original plans have been scrapped, according to Ian Flynn, the writer of the preview on Free Comic Book Day several years ago. Dark Horse Comics hasn’t released a statement regarding this, but it looks like it’s really not happening.
(For what it’s worth, you can check out that preview comic over here.)
Source: Nintendo Everything