There is a long-oil, tung oil varnish product called Waterlox, which is the only finish coating I know of which would serve as a sealer in the situation you described.
Waterlox is available in 3 different gloss levels and has tremendous drying power, more than any other long-oil varnish I've ever used.
A cured film of this finish material is food-safe, and would protect your G10 from water, alcohol, fruit acids and skin oils and food oils, for sure.
At first thought, I was going to recommend shellac as a sealer, but then thought better of it, not as much resistance to water degradation and absolutely no resistance to alcohol.
Hope this helps..!!
Mark
EDIT:
Forgot to mention, the resin in Waterlox is phenolic, an extremely tough coating, which was king of the varnish resins before the days of urethanes.
