The product being sold is not all that uncommon; I think the method of using a transformer down to 'convenience' 120 VAC single phase electrical is the most common way of doing this.
"Power Tap" combines both of those elements into a single enclosure, but it still would take some careful specification on the supply side and require an electrical/ Electrician's license or sub to install.
Also, a variation of switched power at the lamps via photocell is to energize/deenergize the entire leg with one photocell or timer at the supply panel. Confirming the lamps are powered all the time even if not switched on is a helpful step.