Kidney Cancer Symptoms - What can be done?

Hi Everyone... I have posted here before but here is a reminder on my Dad's situation:
My dad had prostate cancer then kidney cancer over 20 years ago. One kidney was removed. The remaining kidney was being monitored and they found two small "lesions" back in 2007. The surgeon we met with was excellent and old fashioned and very conservative and explained to us that he was in a difficult situation because at the time he was too young to risk losing his kidney or kidney function so we chose to do active surveillance. Fast forward, the lesions were stable until June 2024. Not sure if it was the Covid vaccine, shingles shot, or as one doctor (second opinion we went to) his immune system that just changed, but the lesions grew. The larger one was about 6 centimeters in June 2024, the doctor saw him again in September and then again this past February. The larger tumor in the center of his kidney grew to about 7cm. and a second one closer to the top is smaller (I think about 4 cm). The surgeon still explained that at 83, he does not suggest operation because my dad would have to be prepared to lose his kidney and get on dialysis which he said he wouldn't live long on. This plan was scary but we were comfortable with it as my dad was asymptomatic for a long time. However, since about January my dad has been feeling fatigue, no appetite, and losing weight. After seeing a hematologist and his PCP we see that his hemoglobin numbers are low and have been dropping since November. Hemoglobin was last 11 and ferratin was 536, Iron total was 16 and RDW was 16.2. We have been trying to have him eat healthy, drink water, and now have PT to help him build his muscles up. It's been challenging for my mom, myself, and whole family to see the change in him. A few months ago he was a very active 83 year old who would look after my mom who is 74 years old. Now it's in reverse. He sleeps a lot during the day, doesn't want to eat (but does) and has some foggyness in his mind and some memory loss (short term). I think all of this is due to red blood cells which are low meaning less oxygen in his blood. The hematologist and surgeon basically say to manage the symptoms by making him eat healthy, drink water, and exercise (bring PT in) but I don't feel it's enough. The second opinion dr wanted to throw him into immunotherapy the same day and we put the brakes on that. His surgeon said since it did not metastasis, he wouldn't have been a candidate for that and that it would cause more damage than good. We are at a loss and it feels like we are sitting ducks, waiting for him to get worse. We were told he has "very, very high inflammation markers" but that there is nothing to do for it since it's most likely coming from the cancer. When I asked if we could lower the inflammation, the hematologist said that may be his body trying to fight the cancer from spreading. Again, we are at a loss and not sure what to do. I will do anything to help my Dad. Yes, he is 83 but despite the doctor saying he is old, etc. he has siblings alive and well in their mid-90's and it hurts me to see my dad deteriorating. Yesterday he was forgetful. I feel like we are sitting waiting for things to get worse. I understand surgery would be too risky for him but our second opinion thought he should go in immunotherapy but his doctor said he isn't a candidate for that since it hasn't spread. I'm at a loss because the inflammation and his labs being off are making him extremely fatigue and foggy. I appreciate any advice or feedback. Be well and God Bless you all.