Create the communities you want to see here and treat them as completely separate entities, with their own userbase, content, etc. You’ll be the only one posting at first, but if there’s interest it’ll catch on.

You’ve already gone above and beyond by inviting the Reddit mods, and I admire your sense of ethics, but no need to sweat further. In the end, ethically speaking, mods don’t “own” a community, much less the intellectual concept behind a given community; they just start it hoping others will join up. So you’re stealing nothing by creating your own elsewhere. That’s what Lemmy is about, anyway. And if those mods or sub participants ever decide to leave Reddit and they don’t like what you’re doing, any one of them can create their own instance and start again just like you did.

Again, I massively respect your conscience in this. I feel like I’ve seen a unicorn in the wild, lol. But you’re good. Go forth and create the communities you want to see.