...Use a curing finish.
Specific suggestions?
I would not want any type of membrane finish on a cutting board. The finish is compromised with the first stroke of a knife, and you end up with a handy surface underneath which bacteria can migrate. Mineral oil is safe and effective if kept clean. There's a reason why virtually every major cutting board maker recommends and/or sells mineral oil or similar treatments. You are correct, it's a treatment, not a finish, but I don't want a finish on my cutting boards.
...Most cutting boards I see have been lacquered...
My experience has been the exact opposite. I can only recall seeing one or two lacquered boards over the past 50+ years, and they were more for decoration than actual kitchen use.
First of all I had no idea you were old enough to have been observing cutting boards for over 50 years. You are extremely well preserved....