I just got a final email from our vet. The oncologist/surgeon cannot tell whether Einstein would be a good candidate for surgery from his ultrasound alone, so he would need a CT scan first ($2k), and the surgery itself would be $6k-$9k, and that. That is simply funds we do not have.
He's home! He has a massive tumor on his liver (his liver is mostly tumor, they said 🥲). They think it's a hepatocellular carcinoma that could be a good candidate for surgical removal, we're just waiting on the results of a fine needle aspiration to be sure.