Soon, somewhere around version 140.

Hello

This announcement, Firefox Labs. https://connect.mozilla.org/t5/discussions/custom-wallpapers-are-here-with-firefox-labs-in-138/td-p/95308

And, for information purposes. Configuration Editor for Firefox https://support.mozilla.org/en-US/kb/about-config-editor-firefox Enter a search term browser.newtabpage.activity-stream.newtabWallpapers.customWallpaper.enabled Enter a search term browser.newtabpage.activity-stream.newtabWallpapers.customColor.enabled

WARNING from the moderator team: Changing Firefox preferences from the about:config page can sometimes break Firefox or cause strange behavior. You should only do this if you know what you're doing. Please read Firefox advanced customization and configuration options to learn more.

Clarification.

Some people don't see Firefox Labs https://support.mozilla.org/en-US/kb/firefox-labs-explore-experimental-features-firefox.

Note: To run experiments in Firefox Labs, Studies and telemetry must be enabled, which are the default settings. If you’ve opted out of Studies or telemetry, you won’t be able to use Firefox Labs to turn on experiments.

For this reason, I've specified, about:config, for those who are interested.