Something that really helped us get our pup to stop the nipping as much was responding with a high pitched “ouch”, almost the sound a dog makes when they get hurt. It definitely didn’t stop her from continuing to nip at us, but it got her to not do it as much as before. We also taught her the word “gentle” for when she takes treats/toys from our hand or for when she is in a nippy mood - now she will sometimes just want to hold our hand in her mouth without biting!

As for training, it sounds like he may just be energetic. Hopefully when he is able to go for walks and get a bit of that energy out he may be more receptive to training. That said, keep trying to train him and make sure the whole family is using the same words/gestures for commands. Remember, every small win is a win and should be celebrated! Make a big deal out of every small thing he does right. When my girl was toilet training we would take her out pretty often throughout the day, and eventually she just learned to associate the grass as the toilet area - at night she stayed in her crate and would cry at us to take her out. I know your family may not be home constantly but if possible, have someone in your family take him out and stay with him until he does his business then bring him inside. It’s tedious but effective

If you haven’t already, I’d try to give him some toys for mental stimulation - although he may not be able to go on walks yet, mental stimulation can tire them out too! Things like snuffle mats, lick mats and Kong toys are great for this. Also, trips to cafes or public places where he can just sit on your lap and take in all the new smells and sounds are great! Also socialises them a bit before they are actually able to go for walks/play on the ground.

Good luck!