I'm going to buy a proper TTL cable today, wasn't hard to find one once I figured out they're advertised as Arduino cables. According to another post (https://forum.openwrt.org/viewtopic.php?id=46371) those values should be at 0x9F020040 and 0x9F020044... I'll probably try to find out what's in those locations on my device. Never really used u-boot before so if someone want to give me pointers feel free to.
I guess I don't need them to restore a new firmware but it's more for documentation/debugging reasons.