I think the hygiene issue is somewhat exaggerated. Early printing often didn't prioritize properly dried filament so the output often bubbled and had many pockmarks and imperfections where bacteria could grow. If you look at modern prints they are quite smooth and consistent.

Even so, if you want to be perfectly safe then apply a coat of polyurethane varnish and let it fully cure. That will seal any holes or voids where bacteria might grow, insulated from cleaning solutions.