This is how to install Firefox via Homebrew:
brew install --cask firefox
But how to install the 'Firefox Developer edition'?
Everything I tried fails with 'Error: Cask '...' is unavailable: No Cask with this name exists.'
brew install --cask firefox-developer-edition
brew install --cask firefox-nightly
What's the correct command?
I've finally found a solution.
Lots of commands on the internet were outdated.
These 2 commands worked for me in 2022 (still working in 2024)
brew tap homebrew/cask-versions
brew install --cask firefox-developer-edition