You can clearly see that they are Applications under the Kind category.
The .app extension will only show if you have selected to show extensions in Finder> Preferences> Advanced.
Before you started using your scanner with the new iMac did you download the latest drivers and software
or your printer/ scanner. As you can see from your screenshot the dates for the CanonIJScanner.apps are
2015 and 2019, which predate macOS Big Sur.
What exact model of printer/ scanner is your Canon.
Go to an official Canon support website, input the exact model of your printer/ scanner, that should
open up the support page for your model.
For example,
https://www.canon.co.uk/support/consumer_products/product_ranges/printers/pixma/
Make sure the operating selector is set for macOS 11. Big Sur.
You should then see the appropriate drivers and software.
Download and install them.
Restart the mac and try again.
OR, Reset The Printing System,
Reset the Mac printing system to solve a problem - Apple Support
After having removed the printer from the list and re-added it go to the
Default Printer and select your Canon, this should force the mac to contact
Canon and download the necessary drivers for your model and macOS version.
Restart your mac.
Now follow the instructions I gave you earlier.