The default sqlite3.dll installed with Python does not have enable_extensions compiled into it not just disabled as the python docs suggest. Therefore you cannot add spatial extensions to access geopackage spatial featureclasses from Python in ArcTools. If the sqlite3.dll from Sqlite.org was installed in .../Python/Dlls (that is enabled) we could then load the mod_spatialite.dll extension and supplement ArcTools just as is done with the python numpy module for Grid Tools. This could be done for ArcMap (32 and 64 bit) and ArcPro (64 bit) installations.
By the way, for those of you who cannot wait, you can do this yourself now for your own installations if you have admin rights and are prepared to hack.