Yes, the micro:bit processor in the Hummingbird Bit and Finch Robot 2 is the standard micro:bit v1 that you find elsewhere, so you can use your existing micro:bit with either product.
Right now our products work with micro:bit v2 in the programming language MakeCode. We are working to support the rest of our programming languages with micro:bit v2 and should have this functionality by Fall 2021.
Both the Hummingbird Bit and the Finch Robot 2 do require a micro:bit to work, so if you do not already own a micro:bit you should purchase one with your robot.
The power behind the BirdBrain tools + micro:bit connection is that you get two learning tools combined into one! You can use the micro:bit to do separate projects that you would find on their website, but you are also able to take your learning to the next level by adding external components and multiple programming languages with the BirdBrain robots.