I had a house bunny for ten years, she was an absolute joy and such a lovely little spirit.
I would still not get children bunnies. They are really hard work in that they need to have a close eye on them as they can get very ill very quickly, they are super clever so need lots of stimulation and entertainment BUT they don't tend to like too much handling and definitely not from children who aren't as careful as grown ups.
Ours loved cuddles and snuggling up with us but that was luck, definitely not the norm.
You would need to get insurance and you will be surprised how much it will still cost you to have bunnies. If they go in for gut stasis you will have special feed and potentially they need such close careful care they go in overnight Ramping up the cost to a good few hundred.
They also need vaccinations and for their teeth and nails to be checked and clipped regularly.
Very hold and very cold weather can be a killer quickly, another reason I had indoor bun so I could basically always know how she was doing. She had run of the flat (bunny proofed), lots of toys and stimulation and a lovely little life because I was devoted to her and diligent in my care.
Honestly, unless a parent has experience with rabbits and is willing to devote lots of time to them it's an irresponsible pet choice IMO.
The fact he doesn't know their sex and hasn't considered the logistics of getting them spayed or neutered is appalling.
There is no way you should go ahead with this just because your ex has put you on the spot, it would be unfair on the bunnies really.