I have bought the basic Prime Spike set 45678 when I found a bargain (~200€) and have not regretted it. I played with my sons (8 and 10 yrs at the time) with it for quite some time, but coding was not their thing. I am not much of a programmer myself, but we were able to create some fun machines (more freestyle than following instructions/lessons) - we just dreamed something up, then built it (or what was possible with the set), and innocently dabbled in Scratch-like programming to get it to work somehow. While Spike Prime is surely less "easy" than Boost, I think the sensors, motors, and technic parts provide more playability that is not easily outgrown. If you look on Rebrickable and Youtube, you will find many simple to very advanced projects for Spike Prime. So I recommend finding a used set or buying just the key components, enjoy it as long as you want to, and then resell it again.
In my case, my kids outgrew LEGO altogether (I have not), but still play their instruments.