IMO, it can just as easily be done without script.
- start from a date (midnight)
- add minutes or seconds like you want (needs to be integers, if you want high precision, you can add milliseconds as integers)
- format as “HH:mm:ss”
This doesn’t work if the hours value can reach more than 24 hours, but apart from that, it’s quite concise and easy to understand IMO.
dateFormat(
addSeconds(
getDate(1970,1,1),
toInt({Root Container.value} * 60)
),
"HH:mm:ss"
)