Immunotherapy to extend lifespan in terminal Ca - worth it?

A 71M family member has terminal laryngeal cancer (only months left), has a laryngectomy and a g-tube due to severe esophageal stricture. He is considering immunotherapy to extend his life, but the side effects sound pretty harsh. He is asking for input from the family. We are in Canada, so cost is not much of a factor.

From your experience, do clients usually benefit from the extended time that immunotherapy gives them? Or do the side effects make it challenging for them to do the things they wanted to do with their extended time? He wants to spend time with family and do lots of walks/easy hikes.

How much extra time do patients usually get from immunotherapy? How prevalent and severe are the side effects? How effective are the treatments for the side effects?

Thank you!