How can I help my 14-year-old brother grow more responsible and (hopefully) become Muslim?

Assalamu Alaikum! My brother turns 15 next month and he really struggles with basic responsibility. I don’t mean anything extreme - stuff like getting to school on time, studying, and keeping his room tidy. For a bit of background: I reverted to Islam a couple years ago, but he’s not Muslim. When lockdown started he had just turned 9 and there was nobody to supervise his online classes or help with studying. Before that he was fine at school, but that year he almost failed. He was also given unrestricted internet access. Now he’s often late for school, has trouble with some subjects, and generally acts lazy - he complains about small chores (like putting his dishes in the sink), breaks phones, loses things, and spends money without much thought. My family keeps saying he’s lazy, but I don’t think that’s the whole story. I studied with him once and he improved a lot after only a few support classes. The problem is he gets frustrated by small mistakes, drifts off, and is really disorganized. I don’t think it’s ADHD or anything clinical - it feels more like a lack of discipline and too much internet time. He’s not unintelligent at all. I live nearby but not with him, so I can’t wake him for school or set strict rules. I’m also not his mother, so I can’t limit his screen time beyond what a sister can reasonably do. He listens to me more than he does to my mum or grandma, mainly because he needs a lot of patience which they sometimes don’t have. I feel a bit stuck but very responsible for him. I love all my siblings, but I’ve always felt like I should look out for him more. I’m thinking of ways to help him mature. One idea is to pay for a gym or combat sports membership during the long holiday (Dec/Jan/Feb) and give a small allowance, but tie it to doing some age-appropriate tasks - maybe something like editing short videos and posting them (with supervision) so he learns routines and gets a sense of responsibility. That might also channel his energy away from aimless internet use. Has anyone dealt with this? What worked for you? Any practical suggestions? My hope is that as he becomes more disciplined and responsible, I can gently introduce him to Islamic practices so he might become curious about our faith and want to learn more. JazakAllahu khair.