AIO about my FIL not putting any effort into his grandson

For reference I have a 13 month old son. My FIL lives only 5 minutes away from us and has only ever come over once or twice to see our son. He does however often ask my husband if he wants to catch up for a coffee or go for a hike together but often just offers to pick him up.

I understand it’s good for them to have one on one time but I have questioned whether he ever wants to see me or our son. I think I just get a little sad for our son that his grandpa doesn’t really seem to have much of a desire to spend time with him.

FIL and my husband’s step mum have babysat once. We asked recently if they would be able to babysit while we went to a late night comedy show and they said only if he came to them. We told them not to worry about it as he didn’t have a cot to go to sleep there and hasn’t been to their house for a while (my husband has recently had a rocky relationship with step mum) so we thought that would be quite distressing for him trying to go to sleep there.

Another thing is recently my son’s first birthday I wrote a book in the form of a letter to him. It actually became pretty successful and going to be stocked in the BAM stores across the US. This was pretty unreal for me and have really found a passion in writing now. Everyone has been pretty supporting and FIL has congratulated me. My husband asked him today if he wanted to buy a copy (the family is pretty well off). He said they don’t really know what they would do with it. Idk to me it was a little sad they wouldn’t want a book. Like yes it would be nice just as an act of support but more because it’s literally a book about his grandson.

I understand people have different priorities and not all people want to be super involved grandparents. I’m just a little surprised and sad for my son. Especially if he’s catching up with my husband all the time I thought he would want to see his grandson too. I’ve told my husband he’s always welcome to come here instead of go out for a coffee rather than going out so sometimes he can see his grandchild and me but they always tend to go out and if he picks up my husband he they can’t really take a baby without a baby seat.

AIO for being a bit sad about this? I feel a bit silly for being sad about him not wanting the book but it’s more just about what’s underneath it I think.