>>50769629A few. Not including charity shinies.
My first was in gen 3 when the first ever duskull I found was a shiny, so that was pretty cool.
I didnt find another in the wild untill XY When I found a shiny polywag. Since then I found a bunch.
Replaying HGSS I got a shiny sudowoodo while trying to get one with a good nature.
Then Letsgo, I had a shiny rattata before brock.
And BDSP I found a snover.
In legends I found a ton, but I duno if it's because it's just so much easier to find them. I still consider myself lucky. I found a Shiny porygon on my first distortion event. And A shiny Haunter and psyduck first time in the swamp.