This is not an answer to your question, but additional insight.

First of all, great job on your analysis. It's spot on to what I've found out myself.

I've noticed that even a blank Flutter app (created with default settings) has the same freezing behavior on Wear OS devices under the conditions you described. This suggests that the problem stems from how Flutter interacts with Wear OS specifically, rather than an issue within your app's code.

From a technical standpoint, this issue seems to be unique to Wear OS due to differences in how the operating system manages app lifecycles and background processes compared to standard Android devices. Wear OS imposes stricter limitations on background activities to conserve battery life and optimize performance for wearable devices with limited resources (Link).

I'm currently looking this as well and will provide an update on any discoveries.