Okay... he's doing fine as HE possibly can... so ease up. Meaning... don't expect him to become a Rocket Scientist about it in one swoop.
A child WILL err...and they WILL have mistakes, and they WILL have accidents... and they WILL have hit or miss days. NORMAL.
Just don't pressure. He does not have to wear full on clothing/pants at home... just underwear right now. Putting pants on him and then expecting him to manage that (when their motor skills and coordination is NOT coordinated with pottying) is TOO much TOO soon.
My son is 3.5 years old, and he can't pull down his pants yet... much less quick enough.
Just take it in increments. Not in hours, or days.... I'm talking weeks.
I would NOT have him in pants, UNassisted, right now... because he is STILL in the beginning stages of learning.
Potty expertise for the child, will NOT come all at one time... it is a process.... that occurs in stages.
AND you need to accept... that they will have accidents... this is all a part of learning too. Just like a kid learning math. NO kid will be perfect about it and no kid will be accident free.
EVEN Kindergarten kids, have accidents. I know, because my Daughter did... and her classmates.
NORMAL.
Then, "night time" dryness ability... is a WHOLE DIFFERENT ability... this is biological based and has to also do with the myelin nerve development. Night time dryness/dryness during naps... takes a LONG time... even until 7 years old. NORMAL. Per our Pediatrician and my daughter's Teachers.
I NEVER used pull-up for my kids. I let them be naked at home, or just in underwear. When going out... they were in diapers and for sleeping. I did NOT have them in underwear when going out... UNTIL they fully mastered their bladder control... at home. AND.. .a child cannot hold their bladder for a long time in the beginning and when young... not long enough to get to a toilet... and if the toilet is far away, like at a mall or something... they will leak or have an accident or have a painful bladder. This is setting them up for FAILURE.
I also recommend a car potty. When he reaches that stage. I bought ours from www.amazon.com and put in the search word "potty on the go." A car potty is a life saver... for when the kid has to pee and you are stuck in traffic or there is NO toilet to drive to nearby. My daughter is 7 and just recently she used our car potty. It is REALLY REALLY an essential.
All the best
Susan