Several of my friends have done this with their kids with great success! I've done sign language and visual calendars and social stories. There's so much that's online and free!

My son Logan was using pecs in the beginning when diagnosed with severe low functioning autism. It didn't help hardly at all but he took to sign language right away and he was only 2 and actually his first actual communication with me was him signing I love you. Now he is 11 and still signs but does use pecs at school but signs at home and they continue to teach him sign at speech therapy at school.

We haven't really tried it much. We did take pictures of our kiddo with his things. Example : him holding out his sippy cup (thirsty) , him playing with blocks (play), him with food (hungry) , etc. we've done it for about 4 or so months but nothing has really clicked. He just throws the photos around lol. Hope it works out for you all:)

Our son's school uses them for all of their kids.
Even though our son is verbal, we have used them in activity strips and daily schedules, so it isn't an all or nothing thing.
They have worked well for us.
Like @beastybaconbitsmorning
We took pictures of him and made a morning task schedule and he out cat face stickers over his face and thinks it's the funniest thing ever.
So maybe those pecs line drawings work berter than photos :)