Competent starter...?
The Vega graphics on the 2200G/2400G/3400G are the best integrated graphics out of any retail cpu. But that ability relies heavily on not only the amount of ram, but also the speed of the ram, since integrated graphics use a portion of the system ram that's hardware dedicated. So if you have 8Gb of 2133 on that A320, you'll be stuck with basically an equivalent of a slow GT1030 2Gb. That's fine for websites, everyday windows stuff, even 4k video playback without any issue, but anything above the most elementary games is going to suffer.
Even moving upto 16Gb isn't going to help much at all, the 2133 is going to choke any performance gains possible there, added to the half-pint cpu and lackluster pre-rendering ability.
Pcie lanes are the least of worries, lack of L-cache, thread count, bandwidth, ram speeds etc all combined will put a far greater dent in ability than whether or not it's worth it to add a discrete gpu.
The amd APU's are the Toyota Yaris of modern platforms. Doesn't matter if you sink $30Grand into paint, audio, rims & tires, exhaust, cold air kit and NOS, all you end up with is an overly expensive, but rather nice... Toyota Yaris.
(and my bone stock 2012 Dodge Charger R/T will eat it for breakfast)