Unfortunately whilst the Mutley's Hanger review of Plan-G discusses Live Google Maps Integration this was not implemented in v3. As Tim explains:
"It was and is clear that there is no way on earth I can pay Google's $10,000 PER YEAR licence fee, and so the choice was simple: Make a v3 with no Google maps, or shut down Plan-G altogether."
https://www.tasoftware.co.uk/forum/index.php?topic=2557.msg13272#msg13272
Per Plan-G v3.2.2 ReadMe:
Notes:
Maps
PG3 uses maps based on Open StreetMap (OSM) data. This has the advantage of being free and will always be free. The downside is that the servers can be bandwidth limited (OSM themselves get very uppity if you start hitting their server heavily). The preferred servers for PG3 are from MapQuest, which is a commercial company that sponsors a free access server and doesn't complain about bandwidth.
So, I am sorry to report, Plan-G does not use Google Earth/Maps (and has not done so since v2).
Regards,
Dorian