Product recommendations for 2a/2b hair?

My boyfriend has long hair that seems to be a mix of 2a/2b. Some days he has quite a bit of loose curls, but others there’s just waves. He’s never really used any products other than shampoo & conditioner though, and I feel like he could get some more definition in his curls if he had some good products. I’m not really looking for shampoo/conditioner suggestions because he’s happy with the brand he’s currently using, but I’d like to get him some other good products for Christmas. I have 1B hair myself, so I’m not sure what products would even be good for him. Please help!

Note: he hates the “crunchy” feeling that some gel/mousse leaves, so I’m trying to avoid products that cause that.

Second note: he’s currently shampooing and conditioning his hair twice a week, and using clarifying shampoo like twice a month.