Fledgling Wood Pigeon - Age?

Evening all

We have (had) a busy wood pigeon nest in a bay tree in our garden. Got back from a morning out today to find a fox (probably, last night) has taken apart one or two fledglings, parents have left and a single fledgling was left moping about the garden. We observed it for much of the afternoon and shooed off an adult pigeon which returned regularly in an effort to peck it to death (I'm aware pigeon feeding looks like a bit of a struggle, this wasn't that, it was getting attacked, I'm concerned we left it too long if anything). Things weren't looking bright.

After some water and a meal of 7 peas it's in a box in the garage for the night. I'm really hoping we can reunite it with parents tomorrow (if they still exist...) but worst comes to the worst how old do we reckon this little Pidge is, and how long could we expect it to be with us before being good enough at life to take up normal Pigeon duties?

Do they take well to a little hand rearing and return to the wild or do we now have a Pigeon pet? (which is certainly not the objective...!)

It's surprisingly heavy for its size, I'd assumed they were mostly made of feathers, so it seems to have had a decent start...

Thanks in advance!!