Most browsers nowadays are just using the same Chromium engine found in Google Chrome. That means most sites work the same in all Chromium-based browsers, since those sites are tested in the most in Chrome, but they might run into issues on Firefox or Safari. Google's web apps have been far from perfect on Firefox over the past few years, but now many of them are working better than ever in Mozilla's web browser, even Google Meet.
Firefox Now Works Better With Google Apps, Including Meet
Who needs Chromium?
Google Meet (Duo)