GrapheneOS doesn't bundle anything Google to reduce the amount of trusted parties on setup. You trust the device and GrapheneOS and then whatever you wish to add afterwards. Using Google apps are a choice of the user and we don't think they should be as tightly integrated as MD privileged as they are on stock, but we have a compatibility layer to allow them to work for normal users.
You're free to use whatever apps providing they aren't blocking themselves from running on anything that isn't a Google certified OS. If you want to be closer to the stock OS experience you can also check out the Markup app to get the stock Pixel screenshot editor: