The Ordnance Survey have provided a set of FME workbench tools, that will allow you to load the data from .gz files into a GeoPackage.
We have taken the FME workbench tools and converted them into Spatial ETL tools, which can be used by ArcGIS users via the OSMM-Highways toolbox. This can be downloaded from our GitHub repository. Note: You will need to have the Data Interoperability extension to use the toolbox.
During the initial phase of the release Esri UK can provide a national load of the converted data in File Geodatabase format. The data is held in ArcGIS Online and can be shared with organisations that hold a PSMA licence (or equivalent) and who have signed up for the evaluation on the Ordnance Survey website.
Once you have signed up please send us an email if you would like access to this data. Please include details of your organisation and an ArcGIS Online User that we can share the data with.