I believe garmin is actually better than the others.

I've never put my watch online.

You don't have to "activate" the watch or create an account to use it. You can just strap it on your wrist and go.

You can get to your data using MTP (or the garmin protocol) by accessing the watch filesystem.

I'm not certain about updates. I haven't found a way to download and update the watch offline, but I haven't seriously tried. I did notice some beta firmware you could download and update older watches with offline.

So I think you might need garmin connect or similar to download apps or updates.