Yes, for some of them, but not all.

I've not been able to find a convenient online image showing the characters you get from holding down alt while typing, it may vary by layout, but for me this lets me type:

Number row: ¡€#¢∞§¶•ªº–≠ with shift: ⁄™‹›fifl‡°·‚—±

First row: œ∑´®†¥¨^øπ“‘ with shift: Œ„‰ÂÊÁËÈØ∏”’

Home row: åß∂ƒ©˙∆˚¬…æ« with shift: ÅÍÎÏÌÓÔÒÚÆ»

Bottom row: `Ω≈ç√∫~µ≤≥÷ with shift: ŸÛÙÇ◊ıˆ˜¯˘¿

But of those, I only remember €, # (both printed on the key!), ∞, ƒ, ™, π/∏ (thanks to growing up with MacOS classic — Marathon Infinity for ∞, ƒ for folders, ™/π/∏ no idea why), and –/— (en-dash/m-dash, not sure why I learned them, but was one surprise source of compile-time errors around 2010 because they look exactly like - in a fixed-width font).