The last issue on this PureOS Crimson GR: Beta test, upgradable from Byzantium · PureOS · GitLab is now closed and pureos-upgrade package is marked beta (from alpha), so it seems we are pretty close to beta release.
Final release will milestone is 70% complete OKR 2026: PureOS Crimson GR: General release, replace byzantium in shipping · PureOS · GitLab