Pebble went bankrupt because no one bought their products. Their assets were acquired by Fitbit. Fitbit did not continue to produce the Pebble products for which there was very limited demand. Google then later acquired Fitbit.
Big Tech companies acquired and acqu-hired many unsustainable small and medium sized businesses in the past 16 years. Most people don't know that because seller doesn't want to admit they were a bad unsustainable business and buyer doesn't want to admit they are buying a bad unsustainable business.
They sold 2 million units, which is nothing to sneeze at for a Kickstarter-funded project. What they miscalculated was the demand for the Pebble Time, for which they spent too much money on R&D and marketing to justify the results. They should have iterated on the original design, making it cheaper, smaller, and longer-lasting. Instead they tried to go upmarket and compete with the Apple Watch, with predictable results.