You're in Canada, aren't you Greedo? If so read this link
as it pertains to fleas in Canada. The general information is relevant wherever but the products being sprayed are probably one of the listed ones and if I was guessing it'll be methoprene.
As for what it will do to the figures I'd guess nothing. They'll likely apply it where the fleas wouuld prefer to be, so closets, baseboards, possibly furniture. I doubt your collection is going to be touched by the spray because they likely won't "gas" in the sense of a big tent over the apartment or anything like that. There'll be minimal residue I would think.
As always, when it doubt, pack it away. Especially anything difficult or expensive to replace. I probably wouldn't leave a loose or carded vintage item out for that but the modern stuff wouldn't be an issue.