I am very sorry for your loss. Do you want to get a necropsy to see what caused the tumors? Your state vet can do that if you take or send the body to them today. Here is a list where you will find your state vet to call if interested :
https://www.metzerfarms.com/poultry-labs.html
If it is cancer, culling eventually might be a kindness. I would continue to observe him, and make sure that he is not suffering in any way. But I would try to get a necropsy by the state vet if you do cull.
I also noticed the possible smaller one around the right nostril earlier. So sorry that it does look like multiple lesions. It might be good to get a necropsy on him by your state vet if you lose him.
I hope it is not cancer, but it looks like one. A vet would have to perform a necropsy to confirm it. The tell tale sign is the dark crater inside the mass. They can show up in different areas of the body. Broiler chickens can commonly have numerous ones on their bodies when they are being...