Apple referred to AirPort Extreme/Express updates as Firmware updates.
View attachment 90146
There is also DFU mode(Device Firmware Update).
iPhone: What is DFU mode, and what's the difference from recovery mode?
True. But conversely you’ll note there are no software updates for their WiFi routers. Also, I specified iOS. (meaning to include all the iOS related devices).
DFU mode isn’t something Apple ever tells you to do outside of tech support. You won’t see Apple releasing a firmware update and saying, “Hey, everyone, use DFU mode to install this”. So, technically correct, but not something a typical user will ever see (unless unlucky).
In the end, I’m not saying Apple does not do firmware updates. They do. They just prefer not to make them the separate, big deal, that other manufacturers often have to.
Even in the AirPort products, it’s just a notification and click this to install and reboot. None of that “go to this special site, download this file, install, run, and reboot” that most other firmware installations require.