This past weekend, Shiny Ferroseed debuted in Pokémon GO as the featured Shiny release of a series of sponsored events including the Verizon Special Weekend, the GrubHub Special Weekend, and Mexico's 7-Eleven Special Weekend. The Shiny variant of this Grass/Steel-type Pokémon from the Unova Region wasn't just available as part of these events, though. Shiny Ferroseed has been released fully in Pokémon GO for all trainers.
The verification that Shiny Ferroseed was live in Pokémon GO came ahead of the sponsored events in the United States from trainers posting on social media. It's no surprise that this Shiny release wasn't limited to the event, as past events, such as Safari Zone, saw the simultaneous worldwide release of certain Shinies. For example, while the Montreal Safari Zone was kicking off the release of Shiny Yanma, I was thrilled to encounter my own sparkling blue bug on the day of its release of at a hotel in Ohio. Essentially, this means that when a Shiny is released in Pokémon GO in some way, it's generally fully released for all players… with the exception of certain Pokémon, such as when Unown was re-released in its Shiny form for the GO Fest 2020 Make-up Make-up Event (remember that?) for certain timezones.
In any case, those who played the Verizon, GrubHub, and 7-Eleven Weekends had a better shot to start with, simply because Ferroseed, generally an incredibly rare spawn in Pokémon GO, was drawn to Incense at a relatively quick pace. Now that these events are over, it's just a matter of finding Ferroseed, which isn't that easy. It is an incredibly rare wild spawn. Personally, the last time I saw one outside of an event was when it showed up on my nearby… funny enough, at the exact same time it was in its (at the time, underwhelming) run as the Research Breakthrough. Other than in the wild, Ferroseed can be found in 10KM Eggs.