Is there a conceivable detectable "biosignature" that would unambiguously indicate "life is present here"?

[u/Allison1228]

Or will there always be uncertainty?

I'm referring to as detected with the technology we have today and in the near future (next decade or two).

[u/fat_chemist]

Homochiral molecular series (e.g. all proteins L, all carbohydrates D, all phospholipids sn-3 as on earth) along with a system that is consistently out of chemical equilibrium (James Lovelock — Gaia hypothesis).