A friend asked my thoughts on it from a foster care/adoption standpoint as she is trying to decide if it is a safe movie for her foster daughter as she often questions why her story doesn't work out the way things do in kid movies. That was an excellent question, and I wish I would have watched the film with that in mind from the beginning. Since I didn't intend to examine it from that perspective, I am sure that I will miss some things that may be relevant, but I'll take a stab at it.
*I don't want to spoil anything, so forgive me for being vague about some things.*
As you may know from the last installment of the series, the toy gang has found a new home with a preschooler named Bonnie since Andy moved away to college. Bonnie leaves the toys for her first day of kindergarten. She is given the task of creating a pencil holder and in the process creates the newest addition to the gang, Forky. Forky is created out of some unpleasant circumstances and doesn't see himself as worthy of being loved. He refers to himself as trash and repeatedly tries to get away from the group and dispose of himself. Woody is determined not to let this happen and takes on the task of continually monitoring Forky and repeatedly reminding him of his worth to Bonnie.
Forky's insistence on disposing of himself leads to him being separated from the group and of course Woody is on a mission to get him back. With the support of their friends, the journey begins. When Bonnie realizes that she has been separated from her new friend, her heart is broken, and she longs to have him back. Woody, Forky, and their host of friends go through one thing after another to protect Forky and show him his worth. (Some really creepy dolls that look like ventriloquist dummies are involved.)
There is a lot of talk about lost toys and some sadness shown by those who don't have a kid and want one. Some of the lost toys have formed their own support system and no longer wish for a single kid but instead have found ways to be with many kids. Part of the movie is set at a carnival, so the toys that are waiting to be won are in search of their kid. They desperately want a kid and get angry when Woody and his gang seem to be moving in on their territory.
There are lots of twists and turns and quite honestly, some of them were stressing me out! I could anticipate what was coming and wanted them to make different decisions so that they didn't create more drama. I'm not really a high-risk kind of girl.
Woody never gives up on his friend and the gang is all in to help him with his mission. Through the love and commitment of his new friends, Forky begins to realize his significance. In the end, everyone ends up in just the right place. For me, the ending was not what I would have wanted and I may have gasped and been a little too emotionally invested. I may have even made a comment out loud. (Like I said, I was a wee bit emotionally invested.) At the very end, we see a glimpse into the first day of 1st grade where Bonnie brings home yet another creation and Forky willingly jumps in to help this new friend begin the adjustment period.
Personally, there was not anything that was a red flag to me regarding my own foster/adopted child. I think that Woody's persistence helping Forky to see his worth was an excellent picture of what a supportive family would look like for a kid. Woody and his friends go to great lengths and never give up despite Forky's efforts to distance himself. Even when other people told him to give up (including Forky) Woody pressed on.
Every child's story is different. With that in mind, you will need to think about your child's story. I feel like this movie portrays the "lost and found" toys in a positive light. Everything is not neatly tied up in a bow at the end though. There is a different path than you may expect. For some kids in care, this may be a more realistic view of what often happens in their situation. While it was a positive ending, it was unexpected. Sorry for the vagueness on the ending, but as I said, I don't want to be the spoiler.
Side note, I want to applaud Disney and Pixar for including children and toys with disabilities (even if they were subtle).