A relative of mine has a couple flying squirrels. She keeps them in a macaw cage at night where they can run around and play. This cage is easily the size of your average closet.
The cage had to be modified and grid was welded onto it because without it they could squeeze out. Each squirrel has its own wheel made for flyers/gliders, to keep the nails trimmed there is special sandpaper inserts that go on the outside of the special wheels. There is a constant supply of nuts, and bird seed, but fresh fruit and vegetables are given nightly, probiotics are given, vitamin supplements are given, and the toys (bird toys pretty much) have to be rotated out every few months or else they will get bored and "power groom" bald spots.
During the day, they stay on my relative at almost all times. She is their "tree" and they sleep in her bra, they will crawl around from one pocket to another. During the evenings hey spend time with the whole family they belong to and they will jump and glide around, run around.... Doors must be kept shut, toilets all must stay closed when not in use, cealing fans must be off when they are out.
They are as demanding as a dog or cat, except very fragile. These are flying squirrels but the care is essentially very similar to sugar gliders... They both need proper diet and housng, interaction, etc.
It is my understanding that gliders are much more mellow than flyers. Flyers are skittish, like any other squirrel. I'm not allowed to eat potato chips or any snack that has a noisy bag around them when they are out because it freaks them out. They are toilet trained and are taken to go pee on a papertowel on a glass dish three or four times a day. Not making that up lol. They still poop everywhere, but at least they don't pee on you.
With all that said... They are completely worth all the expense, trouble and effort if you are willing to meet their needs. They will proved you with years of companionship and happiness if they are anything like flying squirrels. They will form a bond with you, and will in essence become your little buddy and pal and not so much a pet. For my relative, the squirrels are as much a part of her family as her kids or husband are.