When you point the rented hashrate at the pool of your choice you can see your submitted shares. You can also view the hashrate directly in the Braiins dashboard. This is all discussed in the recent Kratter videos like the one that is the subject of this post. Again, he is advocating for you to mine at a loss for the purpose to signal for BIP-110. He handwaves about possibly breaking even but this is crusading, not a profit seeking recommendation by him.