It worked for my son before he learned how to talk. He was able to “check out” a mini iPad with Proloquo2Go app installed from Zach’s Voice (a non-profit organization that provided communication devices to nonverbal kiddos).

My son was not verbal til age 7+ We did pic exchange, along with sign language & what I called some form of grunt 4 a want or need. It was an absolute destressor & way 4 my son to release stress & be incontrol of his own needs & wants.
It's a time consuming project but once done, it was worth every single pic, hundreds of them & the 10 mini photo albums we put them in.
U must be diligent & committed it makes a difference.
( my dad a ret.physician DO, introduced Rescue 1250 Omega amino acids, my son took 4to6 mineral capsules a day 4 a few months then speech started slowly, but it came & never left thank God.
All the Best)

Sorta depends on the day but mine is becoming verbal

Yes my son now 11 nonverbal and he does pecs and sign little

My son wasn’t nonverbal when he was younger, but PECS did help him. He also had the AAC device. He used it for a while, then refused to use it because he preferred PECS. I think I mentioned this before in a previous post. He used to wake me up by telling me “Wake PUH” (up backwards) and he gave me the picture with an alarm clock.