Hi, whilst I was happily getting the bus into town (Edinburgh) when i was that age and walked to school myself including crossing the road from about 7, I know that my kids are not that street wise and my elder son (he will be 9 in July) would happily go off with whatever stranger asked him. My younger son (will be 8 in August) howled last year when he couldn't find us in a shopping centre, even though he could quite easily walk home from there and has been there hundreds of times. They do however walk the 200 yards to school alone - I can see them from the door! So in my case, I can't see them being ready to get two buses to school on their own at 10.
However, you know your child and what they are capable of. The 2nd bus sounds like a good compromise - why does he want you to pick him up, is it becasue he would have a road to cross, maybe thinking about what makes him more unsure about that journey would help you to understand where he sees the risks.
That;s interesting, because my two are the same, they are happy to walk to school but want to be picked up. I am ok with this, as I finish work just in time to pick them up, so if anything happened to me on the journey home to delay me, I know that they school would keep them safe, however, if they went home and I wasn't there, they are just in the street and I am not sure that they would think to go back to school and wait.