Hola @jmgimo75 y bienvenido a la comunidad, primero si que es cierto que si posteas en inglés tendrás mejor apoyo. Intente simular el entorno que tienes, y creo que con un nodo change podrías solucionarlo, te comparto el flujo para que lo importes en tu proyecto y lo modifiques a tu gusto.
[{"id":"028265c51778150b","type":"tab","label":"Flow 30","disabled":false,"info":"","env":[]},{"id":"860125e741c73f42","type":"inject","z":"028265c51778150b","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"{\"data\":{\"dps\":{\"1\":\"stop\",\"2\":21},\"t\":1681406281},\"deviceId\":\"xxxxxxxxxxxxxxxxxxx\",\"deviceName\":\"Persiana 1\"}","payloadType":"json","x":730,"y":260,"wires":[["67be7cc9649f1701"]]},{"id":"67be7cc9649f1701","type":"change","z":"028265c51778150b","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.data.dps[\"2\"]","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":880,"y":260,"wires":[["1781378dd4cfbb07"]]},{"id":"1781378dd4cfbb07","type":"debug","z":"028265c51778150b","name":"debug 45","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":1040,"y":260,"wires":[]}]
Prácticamente lo que haras sera, almacenar en el payload el dato que te interesa, solamente:
msg.payload = msg.payload.data.dps["2"]
![Screenshot from 2023-04-15 11-22-30](https://global.discourse-cdn.com/business6/uploads/nodered/original/3X/1/1/1163fa7ff774d2eaf650077ccabdf212790bec88.png)
Espero que pueda ayudar, saludos!