8BitDo has just opened pre-orders on their Sega Genesis “retro receiver” as well as their 6-button controller. Both are interchangeable, meaning you can use the controller with any of their bluetooth dongles and the receiver can accept many other bluetooth controllers, including the 8BitDo line of controllers. The controller is $27 and receiver is $25, making it a $52 solution if you need both.
Personally, I’ve had great results using Krikzz‘ wireless Genesis controller called the Joyzz. At just $6 more, I’d prefer the Joyzz, both to support Krikzz’ work and because it was designed with performance and latency in mind, something that’s often much more challenging with bluetooth controllers.
Links for the 8BitDo solutions are below and you can get the Joyzz here: https://stoneagegamer.com/sega-genesis-joyzz-wireless-controller.html?afmc=retrorgb