2006 Suzuki Aerio Won't start, timing belt gone

Hello Folks, our car was driving and parked out front of our house. Wife tried to start it - no luck. I tried and it turned over fine but sounded abnormal. By that I mean there was no banging or smashing heard, it was more an absence of some noises that should be there. The engine was turning over, but it didn't seem like everything was working together.

I don't know a lot, but tow truck driver mentioned timing belt - what I was dreading. After a tow, the garage tried to start it and said new motor needed, timing belt is gone. Estimate repair of 3500$ Canadian for this Aerio SX which is getting up to replacement value of say 4500$.

I've tried to research without much luck. What I can gather is that the 2006 Aerio had an interference engine, and valves are likely bent but cylinders/pistons are likely fine. I also gather that putting on a new belt and giving her a go likely won't be done by any reputable garage, but opening her up and checking for damage is a bit of an investment just to find that there is very likely damage. I haven't had a second quote yet.

It just seems wild for a mechanic to try to start a car and state "new engine" after a few cranks. It's wishful thinking I know, but it just seems like there might not be much damage, changing a whole engine seems wasteful and extreme.

I am scatching my head about why the timing belt and cylinder head can't be just replaced, why do I need a whole new engine? Also, the car was not on the highway at full speed when it broke, it was running fine and the belt seemed to break when we attempted to start it (5 times or so). Would that help minimize damage?