When I visited Finland a few years ago, I made sure that I toured the cemeteries of Vesanto and Rautalampi, the villages my grandparents emigrated from. I found several cemetery stones with Huuskonen and Hytönen (Grandma’s maiden name) engraved on them–but none were for ancestors I knew about at the time.
Cemeteries and churchyards keep records of the location of graves. Graves are often reused after 25 years, and the tombstones are replaced. But the cemetery records generally provide both birth and death dates of everyone who has been buried there.
The Family History Library has not microfilmed any Finnish cemetery records, but the library does have the yearbooks of the Finnish Genealogical Society, which list the gravestones of several old cemeteries. The yearbooks have a personal name index for the first 13 volumes, which cover 1917 to 1929 (to find out what parish graveyards are included, you must search each volume of the yearbook separately):
Vuosikirja: Årsskrift (Yearbook). Lahti: Kirjapaino ja Sanomalehti Oy, . (FHL book 948.97 D25v)
Following up on this approach would give me some additional data on siblings of my grandparents who stayed at home.
The web page further suggests:
If you know the specific area where your ancestor lived, you may contact the local mortuary [hautaustoimisto/begravningsbyrå] for information about burials that occurred after the 1920s.