Another interesting thing in this space is Traindown[1]. It's simply Markdown for your exercises. As an example for those who need convincing to go to a link, this could be a simple workout:
It's much more free-form than this, which is a bonus for me and allows me to track metadata such as weight, time of day I'm exercising at, or general mood/feeling about the workout. I can ultimately just take these plain markdown files from the app (I use a basic Android app that visualizes this Markdown[2]), import them and do whatever processing I like in Python.
Highly recommended!
[1] https://traindown.com/
[2]https://github.com/traindown/transponder