USB-C power delivery safe?
This should be perfectly fine, as it's exactly what it's designed to do. The port in question is a USB-C Power Delivery port and the 2017 MBP supports USB-C PD.

Note this hub is not the charger - it is merely providing the means for your 2017 MBP charger to be used to charge your MBP via the hub. As you're still using the Apple charger that came with your MBP, the actual power being delivered directly to your Mac should be the same, so in that sense there should be no technical differences.