If I'm using side port only for video-out (USB-C to HDMI cable with PD) can I use bottom port for USB devices at the same time? Or do I need to get all-in-one HUB for side port which has video-out and usb ports too for peripherals?
I don't know. Try it maybe?
I know it's not the best reply or anything.
I believe you can charge and use the other USB, it's basically a built in hub. But you can't do lots of high speed things because the side port takes priority
Yes, you can use this side port for anything. I connect this port via a USB hub and connected single desktop screen (via HDMI cable) + USB mouse + USB keyboard+ external hard drive same time while charging the phone from other port. It was working perfectly