You can use the same method to get hard boogers out of a toddler nose as you can to get hard boogers out of a newborn or babies nose.
You can use a salt water saline solution to loosen the hard boogers and then use a suction bulb to help pull the boogers out of the toddlers nose.
If the toddler is able to breathe okay though then it's no harm to leave the hard boogers in the toddlers nose and they will eventually loosen up and come out on their own.
Use a humidifier in the toddlers room as well to help add moisture to the toddlers lungs and nostrils to prevent the boogers from hardening up.
When a newborn baby has hard boogers in their nose and you want to get them out you can use nasal drops that contain salt water to help loosen the dried out boogers.
That will usually get the dried out boogers to loosen up and then come out with a nasal suction device.
You might also need to use a nasal aspirator or suction bulb to help clear mucus from your babies nostrils.
If the baby is breathing okay then it's not gonna harm them to have some dried boogers in their nose and when the air gets moist enough the boogers will moisten up and then you can use the suction bulb to help clear the babies nostrils.
That's what you do as well when the baby cannot blow their own nose yet into a tissue you can use the suction bulb to help suck out snot.