All new features and changes in 6.6 were added in FWTS 25.11.00, along with addressing reported bugs and implementing improvements in this release.
It would be greatly appreciated if anyone can verify their ACPI 6.6 firmware with FWTS and report bugs or missing features.
The source code is available on GitHub: https://github.com/fwts/fwts
For your convenience, the latest live version designed for x86 can be downloaded from: https://github.com/fwts/fwts-live/releases/ or https://fwts.ubuntu.com/fwts-live/
Additional details can be found at: https://wiki.ubuntu.com/FirmwareTestSuite/FirmwareTestSuiteLive