you just need to add .dev_id
after the $'s
i.e.
[{"id":"e4be60a0.551f68","type":"ui_dropdown","z":"e4f02345.29fe9","name":"","label":"","tooltip":"","place":"Select option","group":"8b5cde76.edd58","order":6,"width":0,"height":0,"passthru":true,"multiple":false,"options":[{"label":"","value":"","type":"str"}],"payload":"","topic":"","x":300,"y":120,"wires":[["33dc7075.f3c9e8"]]},{"id":"7d16429b.c68c2c","type":"inject","z":"e4f02345.29fe9","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"#24E1641094172783","payloadType":"str","x":190,"y":40,"wires":[["e4be60a0.551f68"]]},{"id":"e5b387df.b88f7","type":"change","z":"e4f02345.29fe9","name":"","rules":[{"t":"set","p":"options","pt":"msg","to":"[payload.$.{$.dev_id:\"#\"&$.dev_id}]","tot":"jsonata"},{"t":"delete","p":"payload","pt":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":180,"y":200,"wires":[["e4be60a0.551f68"]]},{"id":"33dc7075.f3c9e8","type":"change","z":"e4f02345.29fe9","name":"","rules":[{"t":"change","p":"payload","pt":"msg","from":"#","fromt":"str","to":"","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":500,"y":40,"wires":[["7be18ccf.fe5354"]]},{"id":"5ff0d6fe.d9b3d8","type":"inject","z":"e4f02345.29fe9","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"[{\"dev_id\":\"70B3D57050006F77\"},{\"dev_id\":\"70A3C57050006F76\"},{\"dev_id\":\"24E1641094172783\"}]","payloadType":"json","x":90,"y":120,"wires":[["e5b387df.b88f7"]]},{"id":"7be18ccf.fe5354","type":"debug","z":"e4f02345.29fe9","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":530,"y":120,"wires":[]},{"id":"8b5cde76.edd58","type":"ui_group","name":"","tab":"8f03e639.85956","order":1,"disp":true,"width":"6","collapse":false},{"id":"8f03e639.85956","type":"ui_tab","name":"Home","icon":"dashboard","disabled":false,"hidden":false}]
[edit] set for input payload
if you wanted to do it in a function try
msg.options=[];
msg.payload.forEach((v,i) => {
msg.options[i]={};
msg.options[i][v.dev_id]="#"+v.dev_id;
})
return msg;