Cornflake's advice is brilliant.
"I show him things he’s destroyed and tell him off he hangs his head and seems to know I’m upset"
Please, please stop this. Knowing you are upset and knowing why are 2 very different things. I can guarantee this dog does not link your disapproval to him chewing and so all this will be to him is a random period of upset or anger from you and will damage the relationship you have with him. Leaving him in a crate when out is no problem at this age and - being a husky - might mean it has to continue the rest of his life.
He is chewing because he is distressed at being left alone and chewing/digging is both an attempt to get back to you and something that soothes him. The fact that he follows you everywhere is not helping this so you need to start stopping this.
Give him something tasty and slow to eat (bone, kong, chew) and walk out the room. Come back after 30 seconds and don't make a fuss. Do this enough times that he doesn't both if you leave the room then up it to 1 min. Repeat and up the time out the room until he can do 15 mins or so by himself.
As others have said, you will probably never be able to let him off the lead unless you are somewhere very secure. However, you do need to exercise him. Brain games help tire him out somewhat but this is a dog that needs LOTS of walking/running (think 2 hours a day good solid exercise, at least).
Others have suggested a double ended training lead which may help. First you need to find a harness that the dog cannot get off. Watch for how to desensitise a dog to a harness. Yours will take a lot more tries than the one in the video, but the principle's the same.
Toilet training (in all breeds) can go wonky again at about the 6-8 month mark. Keep the training consistent: lots of praise/treats when he does it right, lots of very frequent garden trips to give him the chance to do so (every 30 mins), don't react when he gets it wrong and clean up indoor mess VERY carefully using an enzyme cleaner to get rid of any lingering scent.
In terms of chewing this he shouldn't: remove them before he tries. I appreciate you probably cannot remove ALL cables but as many as possible need putting away. Ditto new boots which should never be left out. Give him lots of things he CAN chew and instead of just telling him off when he chews something naughty, keep calm, tell him NO and give him something he CAN chew as a replacement. Be consistent every. single. time.
I will add just in case anyone's reading this who is thinking of getting a husky: Huskies are dogs that, when race fit, can run for 14 hour a day and burn almost 10,000 calories. They are independent, smart and not easily trainable. To get ahead of them you are going to have to be smarter than then dog and prepared to put in the time.
They are extremely specialist dogs and whilst some make nice pets, many, many do not (at least not in the hands of someone inexperienced with them). I know a tonne of people who have had dogs all their life, work with dogs etc and many would not take on a husky pet. Their looks are lovely and it attracts many people but they are not easy dogs to take on at all.
OP, that's all not aimed at you because you already have a love the dog but if I can dissuade one unsuitable person from getting a husky because they want a pet dog and like the way huskies look then my mini-rant will be worth it. Everything you have described is typical husky. You don't have an especially difficult one, many are like yours. Anyone thinking of getting one should carefully consider what they can handle.