Daisy with regard to your specific questions....
"So I'm sure they'll send a card and maybe a present, but I'm not having it and not opening it."
It's not your card or present to reject. If the card were abusive or the present unsafe or unsuitable, I would say fine. But a nice card and present from her grandparents in Ireland may be something she will like - IMHO it is not your place to reject it on her behalf.
Re "Am I being too harsh?" Yes you are but I think the reason is you are hurt, on behalf of your dd, which I think at this early stage is unnecessary. And you may well be upset on behalf of your DH, which does seem more understandable.
But your dh is an adult and must work out himself how he feels about all this and what he wishes to do.
You stepping in and blocking Facebook or rejecting cards or gifts seems (although I am sure you meant it well) very unhelpful to your husband's processing of his feelings.
Lastly, Re "In my eyes, they don't deserve to be her grandparents." BUT they are her biological grandparents and it is not your place to decide wo deserves to be grandparents. Of course, if they were abusive I would keep my child away from any such person.
I feel you are stepping in to prevent harm and in this you may actually cause it.
I really think that if this continues, if/when this comes to light (you kept the present/s from her, if this continues) your DD may feel you acted unfairly to her grandparents and made a difficult situation worse.
Please do work these feelings out yourself and I would be tempted to see the 'long game' here; if they are behaving like this in ten years time your dd may still welcome their gifts but won't have a real relationship with them.
This is exactly what happened in relation to my own mum, FOR DIFFERENT REASONS, because my mum had dementia, and in the end could not relate well at all to the kids. She always bought lovely gifts, with my help in choosing, for birthdays and Christmas, because that is all she could do in the end. Now she is gone it is a way that my kids can remember her.
Life is short, don't make it harder on yourself, please OP. 