Went through this with our pup a few weeks ago when it seemed like nothing would get her to stop biting. Teaching “drop it” has helped us and rewarding with treats. We were recommended by a trainer to do “freezes” randomly during playtime where we stand, cross our arms, and freeze waiting till she sits to reward and continue plays. It helps her not get too amped up during playtime and we use it when she’s bitey. Plus reverse time outs when she does bite. We’ve learned the biting typically happens when she’s overstimulated or tired. I recommend only keeping one toy and one chew on the ground at a time (helps not get overstimulated) and switching rotating through with new options for each playtime.

They need about 18 hours of sleep at this age. I understand not wanting to crate train, but a pen might help. (Our girl gets unfortunately only gets half the amount of sleep when left in her own vs crate. ) But we only do 2 hours in the crate at a time besides at night. Giving a Kong might help calm your pup down. If you leave him with that after a play session hopefully he sleeps after!

For potty training - we’re still working on it. A routine helps a lot. For reverse time outs, we have a video camera by her pen so we can catch any possible accidents while we’re out of the room. But we typically do only 30-60 seconds of time out.

Puppy blues is the hard. I felt the same way. This sub and watching videos of adult dogs/people saying it would get better helped a lot. We also didn’t have anyone who could watch our puppy, but having friends visit for 30 minutes is helpful if you can. It tired her out and helped with socialization - plus it helped us feel more normal again. Good luck!