Unknown package: icecat 102.9.0-guix0-preview1

Couldn't find any package named icecat 102.9.0-guix0-preview1. But you can do the following:

1. Ask around if there's anyone working on packaging it (see Guix communication channels).
2. Take this opportunity to learn how to package things for Guix (see how to submit packages to Guix).