[LAD] Find all "beat offsets" from .mscx (MuseScore 3 uncompressed) or exported MusicXML?

Hi, I'm not terribly well-versed in either music theory or the capabilities of all the various musical software tools out there in the happy land of Linux (in my case, Arch Linux). I'm looking to "shortcut" a process: I want to generate two sets of WebVTT captions / subtitles for an MP3 that was produced from a MuseScore 3 file. One set will be chord notations like "F#m/A". (The other will be lyrics. Sort of a karaoke thing with chords.) Since the chord changes fall on a beat, and there are no alterations in the time of this piece -- i.e. no "slower" or "faster" parts, but there are time signature changes, it should be a programmatically solvable problem. The simplest approach seemed to be to generate a starting and ending time for each beat, and go through a parseable file and parse out which chord falls where and attach it to the appropriate element in the list of durations. The thought occurred that, if I have the duration of the file, and either the uncompressed MuseScore or uncompressed MusicXML, there might be a clever tool or Python module to parse the file and come up with the total number of beats, and then divide the duration by that. Rather than invent the wheel from scratch, I thought I'd ask if there was already a wheel -- or if the wheel I'm building ultimately won't roll. ;-) Is this making any sense, and are there such handy tools? Thanx.