Your friend is wonderful! But honestly, I wouldn't go to lunch with him. Your friend is so selfless and kind, but that's too much risk for me. And, as I understand it, restaurant tables are 6 feet apart, but unless you sat at two separate tables, the two of you wouldn't be 6 feet apart.
I've had one friend come over a couple of times to sit in my backyard and have a beer. She knows how careful I'm being and I know she's doing the same. We still sit 6 feet apart. We think we might have a pizza delivered one of these times, but neither of us wants to go to a restaurant. (I've never cared much for going to restaurants anyway, but she likes it and misses it.)
My sister is working at a drive in burger place, she said she never realized how much she needed to watch someone's lips to understand them! I guess some orders got mixed up and she was sure it had to do with everyone being masked and not "reading" lips.