Pampers diapers can be burned.
Although it takes a few tries to get the pampers diapers to burn they will with enough heat burn.
When pampers are wet it makes it harder for the diapers to burn as the wetness in the pampers and wet sap will usually cause the fire if too small to go out.
But if you have a good hot fire going and the pampers diapers are beneath that fire then the diapers will eventually burn.
I've burned pampers and other diapers in my burn pit where I live in the country.
Sometimes there's bits of the pampers or other disposable diapers left after the fire but with a second fire or more stuff thrown on top of it to burn the diapers eventually turn to ash.
If you have a wood stove then putting a pampers diaper or other disposable diaper in it one at a time or a few at a time with a hot enough fire burn the diapers too.
I've done this myself in our wood stove.
While the wood stove is burning I put one or two pampers diapers into the wood stove and allow them to burn fully and with the heat of the stove being so hot the pampers and other diapers burned up with no issue.
Diapers being wet is what makes them not burn properly but the diaper itself once the moisture is gone will burn.