The telling of a Sherlock Holmes tale is a little like adding chili powder when making a chili soup -- with the original Canon of Holmes as the seasoning.
Too much yields a conglomeration of Canonical characters having escaped from their original stories to recombine for a sort of "Canon team-up" crossover like one would find in a comic book. Too little results in a story where taking away the names "Holmes" and "Watson" would leave the tale unrecognizable as something involving our literary friends. (The name of a certain television show comes quickly to mind, but we won't go there.)
How much Canon is "just right" for a tale of Sherlock Holmes?
Ah, but that is the eternal question, is it not?
It probably depends on one's purposes. If one is trying to emulate Conan Doyle, it should be remembered that Sherlock Holmes and Dr. Watson are really not the main characters of the story, but the framing device. The true story is about the client and the case, with our detective duo first learning the "mystery" version of the story, then eventually finding the true facts of the story, one dramatic bit at a time. The main character bits for the detective and the doctor occur in the opening, where we see something familiar enough to recognize our fictional friends, yet not so much that they appear as Halloween costumes of themselves.
Of course, if those Halloween costume versions of the two are "sexy Sherlock" and "sexy Watson," the tale plainly has non-Doylean purposes afoot, and much be taken on the grounds of its alternate universe premises, much as we take Basil of Baker Street or its movie counterpart, The Great Mouse Detective. Sherlock Holmes is a mouse, from there on in, we know we're in a non-Canonical world all its own.
If Sherlock is a mouse or a Hoka, there's a certain comfort in seeing that fact from the start. We don't have to wonder if the writer is attempting Conan Doyle or not. Reading a pastiche that approximates Doyle, however, there is always that initial uncertainty, like entering a swimming pool whose temperature we are unfamiliar with: Is it going to be a comfortable immersion into 221B Baker Street? Or so noticeably warm or chilly that we jump back out of the pool?
It's a very tricky thing, which we've seen done at so many different degrees of success and failure over the years, and will surely see done a million times more before humanity is over Mr. Sherlock Holmes. It is definitely a feat worth the attempt, however, so one has to cheer on anyone who does it purely from the love of those characters that we love as well.
We just have to hope they recognize that they're making chili and not chicken noodle, and season with Canon appropriately.