I upgraded my son from Scratch to Snap! (https://snap.berkeley.edu/). Snap has a much higher ceiling, including collections, first-class code pieces, higher-order functions etc. It pretty openly describes itself as a "Scheme disguised as Scratch" :-)
A pragmatic pedagogical thing I love with Snap! is the ease of creating custom blocks, including macros / custom "C-shaped" control structures. If you have some time, this allows you to "scaffold" helpers that will allow him to create interesting stuff while focusing on things you want him to learn and hiding issues you don't.
* Example: I wanted to teach rendering a custom costume with e.g. health bar or text label. My son is already familiar with Snap!'s turtle-drawing primitives that can render lines & text but there was an impedance mismatch — you draw on the screen, and it does support snapshotting all current drawings to create a costume, but using that involves some careful save-and-restore of much global state (e.g. pen color). I built him a "draw costume" block that takes a body of turtle-drawing commands and affects only current character's costume.
If you ask me, Snap! should have had similar API built-in; but what's more important it was easy for me to add one that looks and feels as-if it was builtin. This way I can decide what I want to teach ("you can compute how you appear") and what is incidental complexity.
A pragmatic pedagogical thing I love with Snap! is the ease of creating custom blocks, including macros / custom "C-shaped" control structures. If you have some time, this allows you to "scaffold" helpers that will allow him to create interesting stuff while focusing on things you want him to learn and hiding issues you don't.
* Example: I wanted to teach rendering a custom costume with e.g. health bar or text label. My son is already familiar with Snap!'s turtle-drawing primitives that can render lines & text but there was an impedance mismatch — you draw on the screen, and it does support snapshotting all current drawings to create a costume, but using that involves some careful save-and-restore of much global state (e.g. pen color). I built him a "draw costume" block that takes a body of turtle-drawing commands and affects only current character's costume. If you ask me, Snap! should have had similar API built-in; but what's more important it was easy for me to add one that looks and feels as-if it was builtin. This way I can decide what I want to teach ("you can compute how you appear") and what is incidental complexity.