That being said, it appears that the main open source version of WearOS (AsteroidOS) only supports watches that are 5-10 years old [3].
I suspect that if you did try to flash this watch, you would experience a whole host of rough edges.
[1] https://9to5google.com/2022/10/21/pixel-watch-bootloader-unl...
[2] https://developers.google.com/android/images-watch
[3] https://asteroidos.org/watches/
Edit: past pixels watches have an unlocked bootloader, I assume this one will as well. I don't see this information in the announcement post.
I'm 100% Google free, and far happier with tech that I ever was.
What's specially shitty with using a wearos watch with an android phone is that clock's alarms etc do not sync, at least not between grapheneos <-> samsung galaxy watch 4. I have to use use turboclock which has a wearos app to get wakeup alarms to my watch.