Where to store interfaces?

Question

Work organization

Server - RESTful API. Stack - typescript, typeorm, PostgreSQL.
Client - Web (Vue, typescript), Mobile (React Native).
There is a need to store interfaces in one place and fumble between projects.
I thought to make a service API resource, where by name to give a scheme from which to generate an interface. But this is just copy-paste for development.
Then I remembered the git submodule.
Someone faced similar?

Answer 1

only rest api. It is necessary to type what the backend can return.

Then why not describe the REST API using the OpenAPI spec and generate code based on it?