I agree, it would be great way to add more life and character to basic waveforms.
A similar suggestion was discussed a while back:
https://forum.renoise.com/t/modulate-sample-start/40039
But one thing that I see as a challenge is that, Renoise being a tracker, we can actually control the sample offset using the Sxx command.
Something like a random offset would have to co-exist with this command - not replace it - or it wouldn’t be as interesting to use, IMO.
So how about a granular playback mode for samples? It would work completely independent of sample/effect commands, be a property of the sample itself.
If such a mode existed, we could control the starting point, perhaps as a percentage of the total size. Any Sxx command would then be added on top (depending on whether the sound is looped, it could wrap around the edges etc…I guess the actual implementation details wouldn’t be simple at all)