@mbonnin is there anything that indicates a lightning talk?

Not in the sessionize API:

{
      "id": "389447",
      "title": "Elevated Gardening with the Kotlin Ecosystem",
      "description": "At-home hydroponics is becoming more popular and accessible. Off-the-shelf solutions and detailed instructions on custom setups are now prevalent online. As an engineer, hydroponics also provides an interesting platform for technological experimentation. With tasty results!\r\n\r\nUsing the extensive Kotlin ecosystem, I was able to build a system which monitors and maintains my hydroponic garden. Come see how Kotlin helped build all of the different pieces: everything from embedded programming on a Raspberry PI, Jetpack Compose on both Android and web, async Spring Boot using coroutines, and all the pieces in between.",
      "startsAt": "2023-04-13T10:15:00",
      "endsAt": "2023-04-13T10:30:00",
      "isServiceSession": false,
      "isPlenumSession": false,
      "speakers": [
        "e975c49f-668a-460a-8ce2-007a36bff35d"
      ],
      "categoryItems": [],
      "questionAnswers": [],
      "roomId": 31925,
      "liveUrl": null,
      "recordingUrl": null,
      "status": "Accepted"
    },
    {

maybe that's inferred by length of talk

That would work!