Is Puppeteer Firefox ready yet?

Unfortunately no.

• Basic features like page.evaluateOnNewDocument() are not implemented yet
• puppeteer-extra technically supports being used with Firefox though
• If automating Firefox is desired use Playwright instead of Puppeteer

Context

• Playwright ships with a custom firefox build, which allows them to patch in functionality as needed
• Puppeteer works with vanilla nightly versions of Firefox. They depend on the Firefox team implementing the Chrome Devtools Protocol and progress has been a bit slow

See also

• https://puppeteer.github.io/ispuppeteerfirefoxready/