USB-C power delivery safe? so I bought a USB-C hub for my MacBook Pro 2017,
specifically, this one:

https://www.aukey.com/products/usb-c-to-4-port-usb-3-0-hub-with-hdmi-port-usb-c-charing-port-cb-c58

it has a power delivery USB-C port, and I'm wondering if it safe for my Macbook to always use that port when I have the hub plugged in (so I can use the other USB-C port on the mac for other purposes) or it is better to plug power directly into the Macbook? any technical differences?
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.