Wondering if my teen has ARFID and how to help

First: my partner (middle aged man) is in anorexia recovery (into year 2). I'm really proud that he sought help and has stuck to his program. For him, he had to focus on just consuming as many calories as possible, and also undermining his notions of "good" and "bad" food that were leading to restrictive eating. As a person who loves food, especially fresh food, it has been a challenge for me to watch him just drink tons of sodas and eat lots of frozen food and super processed sugary foods, but I appreciate that he's doing what he needs to and I want him alive. When he started recovery, he removed any guidance for his son's eating (age 11 or 12 then), like no insistence that he eat some protein food each day, no fruit or veg guidance, no limits on anything. Basically, he treats all foods as equal - there is no attempt at balance or variety, which to me seem essential for good health.

His son has always had narrow/limited tastes which seemed to get narrower as he got into adolescence. He participates in a sport where being thin is an advantage (and where cardio fitness doesn't really matter). He is quite thin but not emaciated. He seems low energy to me most of the time, but he does participate in his sport. Since his dad removed all food guidance, kiddo no longer eats any fruit or veg, and all he eats are snacks from the gas station (candy and soda), chocolate milk, chocolate cereal, and ice cream. For dinner he'll eat either mac-n-cheese, fish sticks, breaded chicken nuggets or pepperoni pizza (freezer-to-oven meals) but often kind of small portions, especially considering he is a young teenage boy, still growing.

Does this sound like ARFID? or warning signs of ARFID? If you suffered from ARFID or other restrictive-type eating disorder as a young teen, what would be the best support you could receive from a parent in a home where you live half the time?