He's not ready, for that phase yet.
Potty mastery... occurs in stages.
Stages.
Not at one time.
That is the way my son started.
THEN when I knew he was ready, per his cues, then I put on padded underwear on him, at home. The Potty Scotty's brand.
Diapers still for going out.
Until he got to the 'stage' that he could hold it longer. It took TIME.
We did not force our kids with pottying.
That just makes things take longer.
AND, once he is ready for going out, with only underwear, I HIGHLY recommend getting a car potty.
I got mine via Amazon.
Put in the search words "on the go potty" and many will come up.
This is a LIFESAVER for pottying children and even once potty trained. Young kids, simply cannot hold their bladders for very long.
IF you are stuck, in traffic or someplace without a toilet or decent toilet, the car potty is a MUST HAVE.
My kids are 4 and 8, and we STILL used it.
It is NEEDED.
Now, for night time dryness and nap dryness, this is an entirely SEPARATE thing, from day time pottying.
Night time or nap time dryness, can take even up until 7 years old, to attain. And it is NORMAL. Because, it has to do with BIOLOGICAL and physiological development of the child's nerve connections/brain/bladder.
My daughter was 5 and still wearing night time diapers.
My son is 4 almost 5 and still wears diapers for nap/sleep time. He is still wet.
The child, does NOT get 'confused' about this, wearing diapers for sleep. Because you simply EXPLAIN to them, that their 'body' is not ready yet, to be dry during sleep.
It is normal.
Also get, a waterproof bed pad, to put directly under him, for sleep. This really makes clean up less of a pain. And the sheets don't get soiled, if there is an accident.
My daughter was 7, and still had sleep accidents. Normal.
NO biggie.
It is their physiological development.
Pull-Ups are USELESS for sleep time, because it does not hold much and leaks.