Scaling up from RWAF guidelines based on 2 hops by 3 hops minimum gives you a minimum floor space of about 6x9ft, but having seen how much mine move I cringe seeing giants in a space this small. Given chance they are just as active as smaller bunnies - we have everything smaller rabbits have, platforms, ramps, climbing places - just scaled up and made safe with barriers to prevent falls. My two share a 6.5x13ft indoor space with a second deck the size of a single bed (it is a single bed!) inside with a catflap to an outdoor space 26ft x 4ft, again with ramps to upper spaces too, but then they still spend 5-6 hrs in the garden as well each day. They get frustrated on the days they don't get in the garden, they are really active when out there.
I guess they eat more but not necessarily more pellets - I feed pellet free but mine have several hours of grazing a day, free hay all over the place, the options of readigrass, oatgrass and dried forage at all times, plus a bucket of foraged wild food or garden plants each day inc herbs. If you get a baby remember they grow up to 18 months which I think is longer than smaller rabbits.
Many people seem to keep them fat though I suspect this is as much due to lack of exercise, but even with mine being fairly lean machines they are big to handle - Freja is still growing but is over 7kg of pure muscle, and whilst I can pick her up for brief moments, she will argue. Odin is a little easier but if he says no, it hurts!! Instead we have worked hard to teach them cooperative care, so they can jump on our knees themselves for checking over, I can check hocks and undercarriage while they sit on hubby's knees for example. Taking them to the vets is a mission, mine go in a large dog crate together, but it takes 2 people to lift them in and out the car in that, though I can load them myself one by one if the crate is in the car already.
They are wonderful little people though, really full of life and character, VERY cheeky. They are still very much rabbits - they can spook just as easily, they can nip and kick, and when they stamp the whole village hears them. But they love to come and climb on us when we lie next to them, and will often go to sleep being groomed or ask us to groom them to sleep which is just adorable.
If you get one, my strongest advice would be to go to the best breeder you can find - ask them what they breed for, what they are aiming to produce - because there are a lot of people who get a couple of giants just to breed them to sell and haven't a clue about rabbits, let alone giants. Babies apparently shouldn't leave until 12 weeks to help prevent stasis. And grow them slow and fit, not fat - they may not weigh as much as other people claim, but they will be far healthier for it.
Oh, and if they go in the garden remember they can reach MUCH higher than you think on their back legs, they can demolish things in seconds, and they can jump and scramble to heights you would never imagine! Be very sure their space is secure!
There are loads of photos of mine if you do a search for my threads
