Stable enough for my initial use-case, light-duty laptop for travel and presentations, running Linux all the time but retain a small ChromeOS volume for firmware updates and restoring settings.
1st attempt I wiped the drive and then found that when the machine attempted to suspect when the lid closed it wiped the NVRAM with no other option to boot into legacy mode than to restore ChromeOS and enable it again.
- Setup base system in ChromeOS
- Fully encrypted Btrfs root partition & ext4 boot
- Install Arch Linux