What I do is teach the dog where the toy box is, and that they may take anything from this box or basket to chew and do with as they will.
EVERYTHING else in the house is mine, and off limits.
So if you don't have a toy box set up, get one, and stock it with a variety of safe and interesting things to chew and play with. For the first week or so, smear several things in the box with a tiny smear of peanut butter or Cheez Whiz. It does not have to be a lot, just a little smear.
Then let your pup have some free time out with you, and watch him carefully. The SECOND he looks at or sniffs at something he should not, interrupt him with an AH AH, that's MINE. Go to him, take him by the collar, and with a smile and in a cheerful voice say "Where is your TOYBOX??" Come on, bud, Let's go find something in the TOY BOX!" Smile and cheerfully take him over to the toy box and make sure he finds a goody with a smear of something good on it. Praise him for taking something from the box.
Play retrieve games by tossing things into the box and encouraging him to go there and pick a toy.
Supervise him very carefully, and EVERY time he looks up at a countertop, table, or pays attention to anything he should not chew, interrupt him, and redirect him to the toy box.
If you are having issues with certain items or areas of chewing, set him up to pay attention to the problem areas, and then interrupt him and redirect him to the toy box, and make sure he finds something particularly delectable to play with or chew.
I have found that having a specific area for approved toys, and CAREFULLY supervising puppies when loose in the house, along with interrupting and redirecting them to the box when they are attracted to something they should not chew works fast and reliably.
Once the dog learns all about the toy box and what is approved to chew, and once the dog is NEVER trying to pick up and chew things that dont' belong to him, you can start letting him SLEEP outside the crate. I usually start this around 18 mos to 2 years of age with the Rotties.
I gate the dog in the bedroom with me at night.
Once the dog is sleeping outside the crate peacefully in the room with you, take down the gate.
when the dog is sleeping and not doing any mischeif in the night, it's then time to start with SHORT times of you being away with him loose in the house. It's smart in the beginning to give him a really cool something to chew when you leave.
Getting a puppy to the point he can be trusted loose alone in the house takes time. Rushing it can cause real issues that are difficult to retrain.
Don't rush to get the dog out of the crate. Take your time. TEACH him what is expected and acceptable. Go slow. Small steps. He's just a baby yet.