Neuroptimal with children

My 8 years old son is using neuroptimal since beginning of december 21. We have rent a machine and he makes a session almost every day. At this moment he have made 56 sessions, but its main problem (AHDH) was not yet improved. He is still struggling with its concentration and focus issues. He is more calm and with more interest in school, but concentration issues are still there.
Can you please share your experiences with ADHD children and neuroptimal?
Another day I have found Mendi device. Any of you have tried it?

Thank you so much