I don’t own such hardware, so not clear about what fails without some wireshark analysis. Ultimately the sane driver is responsible for the discovery, and I think configuring the pixma.conf is a reasonable workaround. BTW, many modern network scanner devices support the use of sane-airscan, so that may be worth trying too.
I can confirm that sane-airscan solved the issue to detect the scanner. Now my scanner is detected without manual IP setting on Tumbleweed. The problem detecting the printer still persist. Any more suggestions?