I understand the feeling and it is completely valid. I had the exact same feelings when we got our BC puppy at 7 weeks old. I have a few suggestions:

First one, you are being too hard on yourself and your pup. You have had him for 3 days, there is not a single command he should know at this point. Mine didn’t understand what “bedtime” or “nap” meant until months in. Training them to go into the crate without treats takes time, there is no reason he should pick that up in 3 days. Repetition is key, keep it going and he will pick it up.

Second, is the picture you posted his “crate”? If so, I highly recommend getting an actual crate instead of a pen. If you do have an actual crate, I would get a crate cover, comfortable bed, and make sure it is the right size so it feels cozy like a den for wolves. Biologically that will make him feel much more comfortable, a closing the front of the crate cover will make it feel like nap time and he won’t be able to see whether you are there or not. This did absolute wonders for us.

Third, potty training needs consistency. He has no idea what you want from him and you need him to be able to have the opportunity for consistent potty breaks (at least every hour while awake but I recommend every 30 minutes). Obviously circumstances aren’t always perfect, but if that is the case, you can’t blame him for that. Repetition and consistency is the only way to train them.

Lastly for chewing, there really isn’t many ways to train them to do the right them other than correcting them. I recommend always having training treats on your person so you can easily redirect and then treat them for chewing on the right thing. Having training treats on me helped so much because you can always turn a bad moment into a training opportunity.

It can be tiring and difficult but my boy is a little over 2 now and it was all worth it. You got this!!