When you get stuck, don't get worried or frustrated. Get excited about getting to play around with a hard problem.
I found that once I actually got an interview or two, it was like a bit of a waterfall. I applied to companies X, Y, Z. When I got an interview at X, I emailed Y and Z and said I'm interviewing elsewhere and if all goes well plan to be in SF, and would love to interview with you. I think this is confirmation bias at play or whatever, because that really seemed to help get additional interviews.
Out of curiosity: is Go actually your most comfortable language? Or are you just interested in using Interview Cake to get some more practice with it?
Not the most comfortable language but a very worth addition!