UEFI specification states that there is a way to work with HII data
from the OS (section "OS Runtime Utilization"), i.e. it is possible to
create a form browser application and read/modify platform HII
settings.

As far as I understand it correctly for this firmware on the target
platform need to:
- use ExportPackageLists() to export HII Database content into a runtime buffer,
- use ExportConfig() to export the current configuration into a runtime buffer,
- provide these buffers via UEFI Configuration Tables

Modifications from the OS in this case are handled via:
- GetVariable()/SetVariable() runtime services (for efivarstore's)
- UEFI UpdateCapsule runtime service (for varstore's and namedvaluestore's)

Is there any known implementation of such functionality?
- Does any of the open-source platforms perform HII Database save
(https://github.com/tianocore/edk2 /
https://github.com/tianocore/edk2-platforms / ...) ?
- Are there any open-source OS apps that can work with HII Database content?