Where are the TypeScript type declarations for Sign in With Google (GSI) library?

1. An NPM package for accounts.google.com/gsi/client does not exist, at least not yet. The only way of using it is via script tag.
2. In addition to @types/google-one-tap from jameshfisher’s answer, there is also @types/google.accounts.

Both google-one-tap or google.accounts can be added to tsconfig types.

tsconfig.json

"types": ["google-one-tap", "google.accounts"]