I don’t know if children long for a perfect friend. It should be the theme of a story – an understanding and sympathetic friend, who was never absent at the wrong moment, and always loyal and able to be really helpful whatever the situation. Perhaps it is not only something for children. We are told of increasing loneliness among adults, as fewer live with others by choice rather than necessity, and much work has become less social (even before Covid working at home).
So when we read Hebrews 7:23-28, there should be points of contact. The writer begins with the way the temple priesthood of the Old Testament was interrupted by the death of successive generations of High Priest. That’s one of the problems with friends; some move away, and some die before we do.
Then there is the point about being perfect. Our friends aren’t, however much we like them and deal with their oddities and failures. The perfect sinlessness of Jesus is awesome, but not alien, because we know he lived and faced all the temptations and difficulties we share (and others besides!).
Of course Jesus is much more than a “friend”, as his once for all sacrifice which meets our need for ever demonstrates. But if this puts him in another category, it does not mean that a longing for a perfect friend is unfulfilled, or impossible. Jesus has met our need, been available – and will always continue to do and be just that. Friend isn’t a big enough word, but it is a start.