Macbooks are such a hostile environment for regular gaming that I would not go that route unless I specifically wanted to tinker more with getting things to work rather than playing the games themselves.
If you're in for something baseline but still nice, I want to mention that a friend of mine got a Lenovo IdeaPad Gaming 3 (Specs: 15.6" / 1920 x 1080 / 120 Hz / Ryzen 5 / 5600H / 16 GB / 512 GB / NVIDIA GeForce RTX 3050 Ti) which I thought was pretty nice for the price. AMD's 5600H is a perfect compromise of price/performance/power-draw and the 3050 Ti has enough power to not be an issue for any game at 1080p.
No doubt there is a clear build quality desparity between such a laptop and a Macbook, but any game your grandson wants to run (it's Jurassic World today but in 6 months it will likely be something else
), he would be able to.
Regarding some other options I'd suggest you look at some youtube-vids
Engadget rapid-fire on 5 popular models.
LTT "How to buy a laptop" - a comprehensive approach to teaching you the details on what to look for and what to avoid. Heads up that the video *is* a year old by now, but most things are still pretty accurate from what I can tell at a glance.