Hi MysteryChicken, as a kid I grew up in Belgium (where they originally come from) and our neighbours did have them (I was supposed to get one baby from them but sadly my dad never build the stable he promised and so my blue Flemish Giant I already had chosen got slaughtered/eaten

)
They need a much bigger stable than other breeds. Well/massive build, because of the body weight. Never take a growing or grown Flemish Giant at the neck skin, they are too heavy for that. Take them under their forefeet and support their bum. If you practice this from the start it will be no problem when they get older.
Congrats on getting a pair, I wish you a lot of fun with this awesome giants!