You want to simply comment on frames or really want ot make the text appear?
For the later you might simple copy a tex object for every new text and change the animatd it “appearance” accordingly…
I heard of :
…but never about using changing text objects with this (but i’m also not very much familiar with grease pencil, so i don’t know the possible text features of it; but for comments…).
And there is always a python solution (okay this might not work today…)
Ohh and of course Geometry nodes… (with switches compareing the frame nuber or drivers… but this may be too complex for a story text…) See also Docs-Blender Manual: GN → TextNodes …
But you may also use the video editor to ad text on specific frames… See also Docs-Blender Manual: Video Editor → Text Strips …
Or some other solutions for “dynamic text” ?