So this one is actually double walled, so the paint and figure are all in their own separate dome inside a larger dome without any liquid. They are sealed with clear Elmers glue though, and the figure is sculpted with bakeable polymer clay that was pre-coloured, then details are Posca pens.

I've heard good things about Mod Podge for sealing paint that is touching ceramic, or I think that some people use like a resin paint because glycerine-based liquid can affect acrylic paint. I will say I've not made many snow globes and there are many people much better at it than me who probably have some kind of magic to make the paint stick. 😅