Nothing surprising here. Why should Canon not work on a fisheye zoom lens for the EOS R system.
Rumor has it that…:
[…] a zoom fisheye similar to the EF version will be coming for the RF mount. It will be an “all-new” optical design and will work just fine on both crop and full-frame cameras.
For the time being, Canon only released the RF 5.2mm f/2.8L USM Dual Lens Fisheye for the EOS R system. The RF 5.2mm aims at virtual reality applications.
As usual, take it with salt. Unless the usual few Japanese sites confirm it, it’s just educated speculation.
Stay tuned, or even better: don’t, and get out taking pics.
Source: Canon Rumors