I have one, however it came from Pokemon Go.
If you play Pokemon Go turn up at one of the community days with your Switch and offer to give people a mystery box, some people will have loads of spare shinies from past Gen 1 community day events on Pokemon Go.
I always told people i didn't care what they gave me as I was happy to help them out getting some Meltan, however a few people i'd got to know from past days community days gave me a shiny Bulbasaur, Charmander, Squirtle and Pikachu between them which was really nice.
Good luck on the shiny hunt! people say chaining shinies on Let's Go is the easiest Pokemon game to do it in yet, however I'm yet to manage it on anything I try lol.