SETI is a "search " for intelligent life, not for "signs of intelligent causation". One is observation, the second is conclusionary.
I think that a pretty good piece of evidence about origins of life all over the universe would result if we were to focus in on the chemical mixes we see in exoplanets, followed by close inspection as qe develop our own technologiws (Im qilling to wait and reserve any conclusion).
I believe we probably will find tht environments on rocky exoplanets will be much Like on earth/Venus/ Mars, wherein(on earth) the events in which life was begun started in a very simple manner .We can evidence the occurrences of a few "false starts"(by virtue of C12 deposits nd evidence of "fossil"chemicals like isoprenes. Chemical evolution seems to follow a fairly proscribed direction once initiate, and all the successive evolutionary changes (I would say that they are directed by virtue of successive "eliminations" of more random ends) seem to follow catastrophic events on the planet that have been used to define the starts nd stops of epochs and Geologic peeiods. (Cryogenic earth, thermogenic earth, presence of water, supwerabundqnce of O2 as a biological "waste product", presence of sulfur catalyses, etc etc).
Its a very simple process and doesnt rely upon a lot of deific futzing or cooking.