Yes, at least according to the Canon support page, macOS 10.14 Mojave drivers do not appear to be available. If you choose OS X El Capitan v10.11as the operating system, drivers are listed. One should perhaps not completely rule out the possibility that these may work, at least partially, with a later system.
https://www.usa.canon.com/internet/portal/us/home/support/details/printers/support-inkjet-printer/mx-series/pixma-mx870?tab=drivers_downloads
To begin with, take a look at the following articles:
If you can't print from your Mac or iOS device – Apple Support
Solve printing problems on Mac - Apple Support
Add a printer on Mac - Apple Support
If no working scanner software can be found, a third-party driver such as VueScan could perhaps be of interest. Regarding printing, just as an example, there seems to be an experimental Gutenprint driver for the MX870.
Generally speaking, ensure that you only download drivers/software from a reliable source. There are several websites, often with names similar to those of the printer manufacturers, where you do not know what you get. Be careful.
Safely open apps on your Mac - Apple Support