Wheelchair DMD advice

Hi, my son who is 6 has DMD and lots of other health conditions. Don’t know if it’s the DMD alone, or combined with his other health issues that also cause weakness and tiredness, but he has never been able to self-propel in his manual wheelchair, which we have had for about 2 years now. We have therefore asked for a power chair so that he can have some independence when we go out. He can still walk inside the home, although we sometimes have to carry him. We are waiting for the assessment but have been told by our physio that our wheelchair service will only issue a powered indoor wheelchair when a person cannot walk inside the home. We will go the assessment, but what we’re after really is a powered wheelchair for outdoor use. We may have to look at funding it ourselves somehow. I’d be grateful to know what power wheelchairs other parents have found useful for roughly this age group. My son is small for his age as well. Many thanks, Chris