As far as I’m aware, the answer is no.
However, as stated by @abhimanyusinghgaur, Dgraph fulfils Spec 3 out of the box. Spec 1 can be achieved by my horrendous workaround. Only cursor based pagination (Spec 2) is missing to be fully compliant and this seems to require a full rework of Dgraph’s generation of the GraphQL API.
There might be a possibility of extending the schema in a way to achieve cursor based pagination but this certainly results in quite an effort. The only way I could imagine achieving this is to somehow utilise the Node interface for this - eg. by assigning generalised edges to all types in your schema (or at least the types which should be paginated). Then you’d need to extend type Query and build custom resolver, maybe similar to @huntersofbook/relay-cursor-paging or use cursor_to_offset from graphql/relay.
However, I’ve not tried any of this since so far we can live with the offset based pagination provided by Dgraph.