There's an alternative to Gutenprint: Bonjour. Canon devs may have left macOS drivers aside, but they did not remove Bonjour support (even though it also only works with the printer. No scanner, unfortunately. :/ )
For me (I own a Canon G3111), all I had to do was the following:
- Download Canon PRINT iOS app (also available on Android). It's important to mention that it'll only work if you have already poured ink and performed for the 5 - 7 min ink preparation);
- Follow the instructions in the manual to configure solely on the phone (which will set up the router connection);
- After successfully connecting it to my Time Capsule (via the iOS app), I opened System Preferences on the macOS, then Printers and Scanners, then '+' to add a new one.
- Your printer should appear right away (with a Bonjour connection). It won't let you add it, so click on the 'Print using' dropdown, select the option to choose the driver from a list, and then look for G3000 (not G3010).
- Add it and test it (with some file or browser; as of my experience, the test page didn't work);
- Celebrate 🎉
Note that the printer supplies' info won't appear. No workaround for that, but you can get access to some settings though your web browser: https://ugp01.c-ij.com/ij/webmanual/Manual/All/G3000%20series/EN/AFG/afg_remoteui.html
(Press the i button on your printer to get network info (IP, password, the works)).
Other alternatives for printing include using Google Cloud Print (you can set it up on the page above) so you can print from Google Chrome (which can be used on iOS too btw... just download PrintCentral Pro. Recommended by Google).
As for scanning... well, it's complicated. SANE (http://sane-project.org) supports this model (tested and approved), but installing it on the macOS is not quite as easy as the only easy method is an outdated app that'll only work till macOS 10.11. More advanced users have tried configuring the backend files (https://stackoverflow.com/questions/53100245/macos-mojave-sane-backends-libusb-not-available-edit-device-is-not-configur), but that's not for everyone, I guess. For now, all I do is to use the iOS app to scan it and send it to my Documents or Desktop folder via iCloud. Works great, but it's not an advanced app.
Some other feature y'all may be interested after setting the printer up: https://ugp01.c-ij.com/ij/webmanual/Manual/All/G3000%20series/EN/UF/functions.html?lapp=ms#category_btn
