I have a 15 year old with ADHD and severe dyslexia.
She struggles massively with a few things, and excels massively in others. She's on track at the moment for a potentially very successful adult career.
It's highly likely that her ADHD and SpLd are directly responsible for both.
Although we didn't get the official Dx for the ADHD until last year, it was pretty clear she was since she was very little, so I've always assumed that she did.
Things that have helped us:
Medication - took a few months of tweaking, but 8 months in she has zero side effects bar needing melatonin at night to get to sleep, and it's had a fantastic effect on focus, fidgeting and she's also a nicer less argumentative child at home! The bedroom still looks like the aftermath of a recent hurricane though.
We focus on what she is good at and making that the most important thing for her, ignoring a lot of what she is bad at (I don't get upset by poor marks in subjects where she tries but struggles - I do with poor marks in subjects she's good at but is being lazy or hasn't done her best). The under-achieving is sad, but I would rather she wasn't stressed out and got lower grades. Finding good tutors early is worth doing to support in the core areas - tell them upfront what the issues are!
Getting lots of tech in place - smart phone with alarms, shared calendars, WhatsApp, school apps like 'Show My Homework', learning to use voice notes etc
Assuming that DD functions at a level 2-3 years younger than her chronological age and so not getting frustrated when she doesn't behave or function like most 15 year olds!
Finding lots of ADHD/dyslexic role models. We are lucky that in DD's main area of specialism it seems that neurodiversity is extremely common. Many of the teachers she has are also ADHD and/or dyslexic and are using similar work arounds to her. She also embraces it and is very upfront about it (it's horribly obvious so good thing!)
Obviously we've been very fortunate that DD has a skillset that gives her a pathway to follow, but my main focus has always been to ensure that she's happy and confident above any A grade or other factor.