>It's as binary as IT

Yup, it either leaks or it doesn't.

IOW in the case of helium leak testing, it either leaks an unacceptable amount or it leaks an acceptable amount.

For higher pressures or stronger vacuums there's always this:

https://products.swagelok.com/en/all-products/fittings/c/100?

https://products.swagelok.com/en/all-products/valves/c/200?

For things like aerospace or energy.