You could coat it with a food safe epoxy or clear coat.

There are definitely a few potential options, I think! Mostly experimental ones though, so no guarantees that they actually work lol. For example:

• Sinter it. Basically print at 100% infill, completely pack it in salt/sand/etc, and heat it in a kiln/oven/etc. The plastic will (hopefully) remelt and solidify without all the pockets inside.
• Seal it with something foodsafe and nonpermeable, some kind of varnish or lacquer, even electroplating maybe. The pockets will still be in there but nothing will be able to get into them.
• Use the 3d print for lost PLA casting instead, essentially replacing it with something else like metal.