You are in the time before Civil Registration in Italy, so you must consult the church records. I did a brief look at some town in the Como region, unfortunately I did not see any church records.
It is unlikely that Catholic Church records will be put online at FamilySearch in the foreseeable future because of theological differences between the Catholic Church and the LDS church.
You can try writing to the specific parish, if you know it. My understanding is that chance of getting a reply is slim. The larger towns will have several parishes. The civil birth records may name the parish where the child was baptized.
Another option is to look through the earliest marriage records.
If the Allegati matrimoniali are online, these files will have additional information relevant to the marriage that may add some earlier generations.