Frog and Toad Are Friends
by Arnold Lobel
Early reader · ages 4–8 · grades K–3 · 400L · 64 pages · 2003
Why we'd hand it over
The foundational friendship book—short chapters, Lobel's illustrations do half the work, and kids understand without being preached to that showing up for someone is what friendship means.
What parents said
Frog and Toad Are Friends is a good one! Not a chapter book like the ones you've mentioned but the stories can be on the longer side.