I'm not sure if I'm understanding correctly so I apologise..
but is she currently an outdoor bunny?
the problem is is that this time of year rabbits have their fur coats that they can't ofc just take off. by bringing them inside to our nice and cozy homes can cause a number of issues. those can be overheating & GI stasis. and as they try to shed their coats as fast as possible to adapt, they can end up ingesting a lot of fur and end up unwell from that. its generally not recommended to move rabbits about when there is a temp difference of more than 10c.
I'd imagine that your house is much warmer than outside and the temp difference is more than 10c if you were to bring her in. generally the "deadline" for bringing rabbits in is october, sometimes earlier. the point that you can start putting them out again is usually late spring, so april/may time depending on the weather.
if you were to bring her in she'd need to come into an unheated room, the same temperature as outside, and then slowly up the temperature a couple of degrees every few days to allow her to adjust and shed her coat without such stress or worry. the chances of her over heating (which could cause GI stasis) would be high and not something I'd want to play about with.
I don't have much experience but I'd imagine a kitchen really wouldn't be suitable for a rabbit. I would worry about them getting underfoot when cooking. I also don't think the temperature changes would be ideal either.. with the heat from cooking and then possible cooking (we open a window when we cook letting the kitchen get quite cold). for us we also have tile flooring which gets rather chilly over a night time. with the constant temperature changes happening I wouldn't think a kitchen as a suitable place for a rabbit to be.
I'd also worry about how crafty some can be, even at an old age. I've known rabbits get into cupboards on the floor, jump up onto counters or even get to on wall cabinets. I wouldn't personally trust myself not to leave something on the counter, which said rabbit could get ahold of. or get into a cupboard or something. it could prove fatal depending on what it is.
I guess for me I treat rabbits much like small children, so I wouldn't want them in the kitchen due to the the amount of risks.
I don't have much advice with young kids as when I had my nephew over he was very intent at getting to the rabbit trays and trying to eat their poop, or put their toys in his mouth. neither which are sanitary :lol: he was about 1 at the time, so he didn't really understand. I think most kids would try though, especially when they're at that mouthy stage, so I think its about trying to find ways of stopping them.
if you're able to do a bit of DIY, you could get a hutch, and then attach a cat flap to it. if you keep the main doors shut and the bunny went in an out of the cat flap, he wouldn't be able to get in and get to her poop toys or hay to eat. well, he could stick his hand in but if its out of his reach it might work? or a run around door in the hutch? if she's able to be free range in the lounge 24/7, you could just get a small cheap hutch to use as her base. if not, you'd probably need to invest in a large 6ft one.
if you're able to keep her free range, you could also get one of those rabbit cages. they have small openings at the front. once again your boy could stick his hands in, but if you can place them in strategic places where he can't reach, it could work. but to be honest with you these rabbit cages really aren't suitable to be ever locked in, not even for half an hour in my honest opinion. so if there is time where she needs to be locked up, I wouldn't suggest using this idea.
its the ferplast Casita that I'm thinking of, this is the 120cm version and you can see the small opening on the front. your boy wouldn't be able to get inside inside, like crawl inside, compared to those that open up the front fully. I used one after a surgery, and eventually joined the two of these together to make one big cage.
https://www.zooplus.co.uk/shop/small_pets/hutches_cages/rabbit_cage/120_cm_cages/95868
they also have a 100cm version but its really really tiny once you put anything in it. 120cm might spare better for putting things out of his arms reach
https://www.zooplus.co.uk/shop/small_pets/hutches_cages/rabbit_cage/100_cm_cages/95880
I was gonna suggest a dog crate to put her in, so that would be her base but if you left the doors open your boy could definitely get in there.. I'm 5ft and can fit in them perfectly fine. perhaps you could get one and put him in the dog crate while she's out :lol:
I would also suggest a pen, but once again most of the doors are huge so if you left her out he'd be able to get in.
either way, its just my two cents and possibly some helpful ideas
I hope you figure something out x