The key is math- no point worrying that your HS doesn’t offer AP Bio if the foundation in math is weak.
I’m not sure I follow what thealternative is trying to learn here-- obviously, recent and rigorous beats a few years ago and not so rigorous. But you can’t take what your HS doesn’t offer, so don’t worry about that. Focus on what IS available.
I’m not so into declaring a kid a wannabee engineer if he hasn’t taken any advanced physics or chem as a junior or senior… these are the kids who won’t know what hit them freshman year of college! So my advice would be to slow down. There’s no point in being a “stronger potential engineering admit” if the kid hasn’t taken enough science to know if engineering is even of interest!