It should be easier since antibodies are much larger in size than viruses, thus easier to detect. A test can be performed with a drop of blood. The only hold up right now is hesitancy of the FDA, due primarily to Chinese manufacturers who are flooding the market with antibody tests that don't work.
A few days ago I posted a news article from the San Jose Mercury news, about several testing efforts, and either the same thing, I heard about efforts from Standford.
In my locale, many people report bad colds back during the Nov-Feb timeframes.
Evidence seems to be mounting that many have had something, possibly Covid19.
But little is known beyond that, for instance if a person testing with antibodies, is permanently immune, etc.
It continues to be a subject with many unknowns.