UPDATE: the original guide described a method that used a mix of
administrator (personal) and standard (work, brew) accounts to better
separate permissions. That setup had a lot of edge cases where things
didn't work well, mainly when brew needed root permissions to install or
remove something outside its /opt/homebrew directory. You can still
check this older version at nomnp.com/plaintext/oldmultiuserbrew. This
new version should work but you won't really have any separation between
users besides macOS' defaults.

 1. System Settings -> Users & Groups -> Add Account
 2. Create Administrator account "brew"
 3. System Settings -> Users & Groups -> Add Account
 4. Select "group" from the drop-down menu and create a group named
    "brew"
 5. System Settings -> Users & Groups -> Click 'i' on the "brew" group
 6. Add your personal, work, brew users to the "brew" group
 7. sudo chown -R brew:admin /opt/homebrew
 8. sudo dscl . create /Users/brew IsHidden 1
 9. sudo chflags hidden /Users/brew
10. sudo visudo
11. Add "%brew ALL = (brew) NOPASSWD: /opt/homebrew/bin/brew" (without
    quotes) at the end of the file.
12. echo 'alias brew='sudo -Hu brew /opt/homebrew/bin/brew $@' \
    tee ~/.zshrc | sudo -Hu  tee /Users//.zshrc
13. echo 'export PATH=$PATH:/opt/homebrew/bin' | \
    tee ~/.zshenv | sudo -Hu  tee /Users//.zshenv
14. source ~/.zshrc ~/.zshenv
15. echo 'export PATH=/opt/homebrew/bin:$PATH' >> /Users/brew/.zshrc