Who's stronger
Even without Andrius soul fragment, Varka was capable of defeating corrupted Dvalin. With soul fragment, a tired Varka survived fighting 10% Rerir and forced him to retreat but ended up with injuries. A fight between him and corrupted Boreas in Nod Krai ended in a stalemate. I personally agree Varka is God-level and comparable to top 3 fatui harbingers even without Andrius soul fragment.
Wanderer easily beat Shouki No Kami who Sumeru Traveler and Nahida couldn't beat directly. Nahida needed to loop 168 times, collect wisdom from her people and buff the traveler to beat Shouki No Kami. Nahida outright says Shouki No Kami has become a true god and later says that the top 3 fatui harbinger rival gods. So I personally think Wanderer is god-level even tho some say he's weaker after sacrificing his power to erase himself from Irminsul but he got revived without anything interfering which means he also has the power Ei gave him.
But we have almost no info about how strong Wanderer is aside from what I said. Hopefully Luna VII gives Wanderer more screentime in fights.