I’ve been building free Garmin apps and watch-faces since 2016.

Any developer can download the ConnectIQ SDK and freely publish an app or watch-face in the Garmin App Store. Does not require any license to build, install or publish an app.

That definitely wasn’t true when I developed my watch face (https://github.com/kelnage/digital-simplicity) - the Garmin IDE compiled it down to a single IQ file which can then be transferred directly to the device via USB.

Of course if you want to distribute it via their App Store you have to apply (it was free when I did it), and the way changing settings used to work (through a convoluted path on the connected mobile device and via the store) it was often best to do that. But you could also use the settings file software Garmin included in their IDE to do it (or now do it directly on the device).

Afaik if you have the watch locally available you can just connect it to your PC and deploy it there.

Even the SDK is available for "free": https://developer.garmin.com/connect-iq/overview/

This is not true, has not been true for years, and probably was never true at least since the public release of their app store.