Gateway versus Dongle

It was only thanks to reading some stuff on here that I discovered Zigbee and as a result, bought a dongle. However I then realised that I didn't have a home assistant setup or even anything to plug my Zigbee dongle into. I reoriented myself and bought a Zigbee gateway and then added a bunch of Zigbee devices to it.

Christmas however finally came around and I finally got my Raspberry Pi, so now as I'm about to finally sort out my dream Home Assistant setup, I'm left with the question, do I get rid of the gateway and just use the ZB Dongle E or do I use my existing gateway? What do you all recommend?