Before you buy anything, I would see if the Superhub 3 is good enough for you when using the Quest 2. It doesn't get great reviews.
And, yeah, you will need to run that Cat 5e cable between the PC and the Router. The powerline connection wouldn't be fast enough.
Since you have a Vega 64 your best bet is to use Virtual desktop. Just make sure you buy it on the Quest 2 store. You could try Air Link first and see how get on, but, the codes Airlink uses work better with Nvidia cards. In Virtual Desktop you can choose between codecs and pick the one that works best for the GPU you have.
Copy that.
Just got the Quest an hour ago so going to have fun without the PC for a few days. THen see how I get on with the Superhub 3
Thanks!