Everything OK.
After a cancelled shipment without any notification, I decided to lend this seller another chance. This time around, the order arrived in 14 days as a tracked Aliexpress shipment. The three shipped TTGO T18 Energy's are all version 3.0 dd. 20190410. The board seems to be working all right. The power switch is only functional when the device is battery operated. When charging, the device is always on. Interestingly, there are provisions for a BME280, but the active components are missing as per factory. The documentation can be found on GitHub under LilyGO/LILYGO-T-Energy