The nice thing about JS is that there is not very much overhead in setting things up, debugging weird things, restarting.
I would propose a simple program with a few steps, it can be a console one, to draw a circle, to draw a rectangle, to draw a pink unicorn ;)
Happy, for me, I don't have such problems. My girl wants to be football player.
We did it with cardboard, poster board, markers, tape, etc, and built a real-life model/mock-up of the game first. Then we let them play it and only when they actually liked it did we code it.
I found that while some kids want to learn to code, most kids don't care about the code and want to make a game. So if you jump straight to code, you actually make them lose interest. Make the coding a phase 2 once they already know the game is fun.
As a bonus I also think that if we create conceptual game assets in the pen and paper way first - say a 60 second drawing of her beloved unicorn - she can use some quiet time later to make it more elaborate.
Funny how this is somewhat of an endorsement of vibe coding a prototype.
So "gamified coding" it is. Online platforms with simplified source code (but still actual code), making little animals move on the screen, by using code, to solve challenges. She already did more than 300 such challenges and understood loops and variables. She begins to understand how functions do work, side-effect, pure functions, etc.
But the thing is: she's 11 y/o. I'm the boss. A nice boss, a gentle listening boss. But I'm the boss. I get to decide whether she can spend 16 hours per day in front of screens playing or not (she can't). I get to decide how many time she can play out in the street with the neighbour's kids (as I type this she's doing just that) and how many hours she does maths, code, etc.
Then I apply concepts between maths on paper and code. For example she loves having one variable named "O_o" as a joke.
This shows a great understanding of what a variable is (although a poor choice in naming it!).
Then we do maths, on paper, and I literally generate her exercise on paper sheet with:
O_o = 3 * x + 2 * y + 7
Find me the value of O_o for the following values of x and y.
She'll be a rebellious teenager soon enough that, as of now, I still get to decide ; )
P.S: at 11 y/o she doesn't have a phone yet either. That shall come soon enough too.
P.P.S: space repetition too. For maths for example... I see where she's struggling, then it's space repetition mode. I generate her custom exercises and three times a week it's hammering.
Two approaches: either build as many games as you can, or create a couple physics-based games that can be dissected and modified for insight on mechanics.
Penguin Jumper and Tower Smash highlight Scratch's ability to simulate game physics. They are from Code Your Own Games! Twenty Games to Create with Scratch (2016) by Max Wainewright.
Likely not much can be done on a weekend versus months; regardless of the technology, have at least one "Wow, amazing" thing from community or Steam to show what's possible.