For some reason many people do not spot the circle icon with dots in so I do not want to hide the activity-specific settings in there.Maybe just add them all at the bottom, so you don't have to go down another level.
I don't think it is that hard, actually when setting up an activity I think it is quite naturally to expect where to look. The only exception is sensors. I would expect Sensor pairing to be global, but I quite like and prefer that it is activity specific. If I recall correct my garmin connect to Stryd if in range and inform me for activities, where I don't even use Stryd. Or maybe it is Polar ?. A HR-belt is another matter though (I don't have one), but I guess that is just a matter of pairing it in WatchOS settings.
All theoretically for me since I don't have an HR-belt yet (don't like wearing them, though I would like HRV), but now I just start to wonder what would happen, if you want HRV and have paired HR-belt both an WatchOS and Workoutdoors. Maybe even with an HR-belt like the Polar H10, that support dual BLE connections. ?
You could keep a global default settings for each of them, maybe below a "Activity defaults" menu-item (because I still find settings to cluttered), which is overruled by activity settings if defined. You could also add a button to the activity settings, that would reset to global default (basically clear them). Also in both places have a text telling, that you can adjust those settings for specific activity under an activity and you can define global settings in settings. You might also add a button in global settings for each of the categories, that would replace activity specific values with default for all
activities, that should require a confirmation to avoid accidents.
I agree it might require a bigger restructure of the app, but I think you underestimate how much time user spend to locate a setting for an activity, especially when there is a lot of unesserary visual noise to filer (disabled activities). Users might also not discover many features, since they simply are hard to navigate to when you are looking for them.
As an example from a me as a user. To simplify the Screens page on the iPhone app, so I easier can find the activities I use and configure them. I have entered every single other activity I don't use and cleared every single screen they had. That is a lot of work, but saves me time in the long, when locating the screens I want to adjust. They are still on list, but since they are empty, it is easy to see I should ignore them. If I ever need them, I can always restore default (but more likely, I configure a screen from scratch with just the data I want and nothing more).
Where is that? 4 is in the lower end for me. 10 would fit. But better than nothing, Maybe, Since would like to keep them fixed on the watch.
Other sports watches keep the order but start showing the last one as default selected. I don't quite know how to do it in WOD. Either scroll down the main menu to last used activity when showing or have a top level menu-item with last activity type or a button that scrolls down to it.
I will bear your suggestions in mind if I have to rewrite the UI for the always on display.