只需将setup()设置为根选项:

/* plugins/provide-apollo-client.js */

import {provide} from '@vue/composition-api'
import {DefaultApolloClient} from '@vue/apollo-composable'

export default function ({app}) {
  app.setup = () => {
    provide(DefaultApolloClient, ...)
  }

  // Or, use local mixin
  app.mixins = (app.mixins || []).concat({
    setup () {...},
  })
}

/* nuxt.config.js */

export default {
  plugins: ['~/plugins/provide-apollo-client'],
}

虽然对nuxt-ts不太熟悉，但是我认为代码应该可以正常工作.

Not much familiar with nuxt-ts though, but I think the code should just work.