I've tasked myself with trying to get a full shiny living dex this year, making a ton of fast progress using gen 7 RNG manipulation. I know some folks see it as cheating, but I'm only getting these for myself (and anyone that wants one for themselves!), and I enjoy the process of it!
Some RNG manips are straight up harder than just hunting them in SV tbh. Anyone can get/buy a Pokemon Home account with 1000 genned shinies if they wanted to so it's up to you to determine what you consider "legit". I enjoy hitting timing required to get shinies through RNG manips so I do it. Some people think gen 9 shinies are too "cheap" and others don't use shiny charms and only hunt full odds (but still hunt on multiple systems at once for whatever reason). It's a weird rabbithole to go down so just do what you want. No one is going to grade your shinies.
That's 100% my stance, I feel like RNG manip is a way to reduce time in a way that requires a little bit more skill. I think having the ability to add challenge by removing certain factors (shiny charm, mass outbreaks), or by hunting specific versions of shinies (huge, tiny, marks, etc) are part of what makes Pokémon so much fun.