Database
db={"users":[{"_id":{"$oid":"600365521599912a5c814e5e"},"nombre":"Andres","correo":"oachica@gmail.com"},{"_id":{"$oid":"600365e9ccf1e51b2cab341f"},"nombre":"Andres","correo":"cachi777_@hotmail.com"},{"_id":{"$oid":"6004591536a40941f48121f9"},"nombre":"Laura","correo":"w.l777@hotmail.com"},{"_id":{"$oid":"6004596936a40941f48121fb"},"nombre":"Javi","correo":"jocta@hotmail.com"},{"_id":{"$oid":"60047cf23f3f1a0d647cb2c7"},"nombre":"Lina","correo":"lvelas@hotmail.com"}],"nodes":[{"_id":{"$oid":"60035d0a1599912a5c814e58"},"idUsuario":"600365521599912a5c814e5e","nodoPadre":""},{"_id":{"$oid":"60047e6874cab54a7088ca56"},"idUsuario":"600365e9ccf1e51b2cab341f","nodoPadre":{"$oid":"60035d0a1599912a5c814e58"}},{"_id":{"$oid":"60047f42c89add3c20cff990"},"idUsuario":"6004591536a40941f48121f9","nodoPadre":{"$oid":"60047e6874cab54a7088ca56"}},{"_id":{"$oid":"60047f5dc89add3c20cff991"},"idUsuario":"6004596936a40941f48121fb","nodoPadre":{"$oid":"60047f42c89add3c20cff990"}},{"_id":{"$oid":"600480de9fd6a42b40679e6d"},"idUsuario":"60047cf23f3f1a0d647cb2c7","nodoPadre":{"$oid":"60047f5dc89add3c20cff991"}}]}
Query
db.nodes.aggregate([{"$graphLookup":{"from":"nodes","startWith":"$_id","connectFromField":"_id","connectToField":"nodoPadre","as":"hijos","maxDepth":4}},{$unwind:{path:"$hijos",preserveNullAndEmptyArrays:true}},{$addFields:{"hijos.idUsuario":{$toObjectId:"$hijos.idUsuario"}}},{"$lookup":{"from":"users","localField":"hijos.idUsuario","foreignField":"_id","as":"hijos.idUsuario"}},{$unwind:{path:"$hijos.idUsuario",preserveNullAndEmptyArrays:true}},{$addFields:{hijos:{$cond:[{$eq:["$hijos",{}]},"$$REMOVE","$hijos"]}}},{$group:{_id:"$_id",hijos:{$push:"$hijos"},idUsuario:{$first:"$idUsuario"},nodoPadre:{$first:"$nodoPadre"}}}])