It doesn’t.
Well... Not from Framework. I looked one up and it was £700 for the main board or £1300 for the whole laptop. Or I could get a laptop with the exact same CPU (Ryzen AI 7 350) from Asus for £800. I mean, sure it's probably not as good a laptop. But even so... If your laptop breaks are you going to spend £700 on a new main board that might fix it, or £800 on a new laptop that definitely works.
It definitely doesn't make sense for upgrading - you can just sell the old laptop and buy a new one if you want to upgrade.
Tbh I hope they succeed still, but it's really hard to compete with the sheer pricing power of less modular products.
This just seems completely unimportant compared to them locking down Android.