At this point GPS is a ‘dont care’ from TTN operation perspective, and the key task of starting the concentrator, so what you want is GPIO17 = Pi HAT 40 pin connector pin 11 for the concentrator reset (SX130x reset) as shown
I dont use this software for my systems specifically so can’t tell you from memory where to look (did know a while back but caches flushed!), last time I played with it was (I think) the Things Summer Academy, or the months following, a couple of years back! and dont have time right now to go digging… others may step in quickly and point you in the right direction…