Is the 737 Max's AOA disagreement warning light an actual light?
In the B737MAX, being a full glass cockpit, the light 'AOA Disagree' is indicated by an alert on the PFD (rather than a physical bulb). This is why Boeing was selling it as an option: it is just a software change to show or hide 'AOA Disagree'.



Image taken from B737 MAX FCOM 10.10.33