Hello @NiWaRe,
Apologies for the delay in response. Adding Lightning support to Opacus will certainly electrify it. Thank you so much for working on it.
What took us so long to respond you ask? Well, we have been working on a major refactor to Opacus (v1.0), and this would mean breaking API changes and code movement. Would you mind sending a PR on top of GitHub - pytorch/opacus at experimental_v1.0 3 branch?