Note: LineageOS for SN:2021 (Emerald) has been pushed without Google Apps. Builds with Google App support should be pushed out soon.
LineageOS 19.1 is out for the Teracube 2e SN 2021 (emerald). Teracube 2e SN 2020 (zirconia) is still a work in progress, owing to the commonization of the code available at github.com/teracube-mt6765-devs.
Kernel source is up at github.com/arcadia-oss/mt6765, branch emerald-s-oss.
You are welcome to build, test and contribute to the code.