It's a challenge to navigate this stage. Each child is different.
Since it hasn't been mentioned yet, I'll say it:
Your DS is quite young. He may not be ready for what you expect of him. My eldest is also a boy & I had huge expectations for him. Those first few years were a struggle until I changed my thinking.
I think at age 7, it's still appropriate to continue the "unschooly" things you've done already.
Be outside as much as you can. Visit museums. Consider subscribing to a monthly science kit or buy a
"gross science project" book & do one of those every couple weeks.
Listen to audiobooks & discuss them as you're living every day life. I seek out books involving boys & high adventure. You're not American, so this series may not apply, but for example, my DS loved
books like this when he was 7. I played memorization songs as background music during car rides and to my surprise, the songs stuck -- DD, at 3 & 4 was learning this stuff, simply through background music.
Is he motivated by earning things? Is there a program with a science museum, scouts, other organization where he can earn badges or patches or *something*? My DS is hugely motivated by things like that.
Is there a planetarium near you? Those shows are amazing & afterwards, he may want to buy an astronomy book in the gift shop and every few weeks, you can make it a point to go star gazing.
Is there a
forest school near you?
Try a bunch of things to uncover something he's interested in & build upon that.
I strongly do not believe a written curriculum is necessary at this age nor do I believe it's the most beneficial model for boys as young as yours.
ETA: cross posted with sweetpeas.
I totally agree with her post.