Hi Swadesh,
Extensions distributed outside of the Chrome Web Store don't go through review, so our store policies don't apply there.
The most important thing to keep in mind is that while we will never enforce all policy through technical measures, we do try to do that when possible. With that in mind, approaches to use remote hosted code that are not explicitly allowed by policy may be blocked by Chrome itself in the future. There is no timeline for this as it is something that we continue to work on over time.
If by enforcing MV3 compliance you mean support for Manifest V2 in the browser, you can see the timeline
here. We will continue to have support in the browser for Manifest V2 until at least June 2025 when enterprise deprecation is taking place. I would expect policy installed extensions from other stores to follow the same milestone.
I hope that helps.
Thanks,