After an unsuccessful foray into Android watches a few years ago, I finally broke down and got a $15 remaindered Fitbit Flex on Ebay. It was advertised as "new/other", but the battery is obviously shot and doesn't hold a charge longer than a day or two, so they refunded my money.
But I still wear it occasionally, to understand the user experience, despite the inconvenience of needing to charge it every day. It's a clever design and does one thing pretty well -- recording your motion and sync'ing to your phone when in Bluetooth range.
For a while I toyed with investing more in a new Fitbit that would capture heart rate, but given how much better Apple watches are both in build quality and likelihood of remaining in business, I think I'll just hold out for one of those, for when I switch from Android to an iPhone 11 or 12 next autumn.
Though, Google might reinvigorate Fitbit, who knows. But Google also shelves products with distressing frequency so it might be a meaningless acquisition. Fitness trackers have become a commodity, with a few high end quality offerings from Samsung and others, Fitbit struggling to retain its market leader status, and dozens of Chinese knock-offs in the $8-$20 range that are mediocre but the price is right.