The following Google Apps Script is designed to get the difference (in minutes) between 2 dates from a Google Sheet. This was part of a tool used to create events from data in a Google Sheet where I needed to get the duration of the meeting for Zoom. The actual date, hour and minute values are separated in columns as it was easier to control user input in that format, so we will need to piece them together.
Source: The Gift of Script: Get the difference between dates in minutes
I use Google Apps Script to support staff and students in my job. I enjoy dabbling with creating tools to help with automation and I freely share my learning experiences on my blog: www.pbainbridge.co.uk