I have a typescript pulumi stack exporting some stack outputs — is there a way I can use the exports from another (non-pulumi) typescript script in a type safe way? Will it work to just import the module in which the stack is defined?

don't think so, if you try and use pulumi without the cli atm you run into a bunch of issues. If you just want to use the outputs and you're feeling brave you could write a script that outputs the json and use something like this to generate the types: https://github.com/shakyShane/json-ts