I think that the other big con for idea 3 is that this is very likely to follow an enterprise sales model. Security in general is the kind of thing that is purchased relatively high up in an IT org. Not 100% clear if your idea would be in that basic mold, but if the model is that the tool runs against or sits on all servers, that would almost certainly be the case.

If you are in the "enterprise" space, that means salespeople, RFPs, support, etc and since all that costs money you are much more tied to a traditional vc model. That could be fine depending on what you want, but it feels different from the other ideas in terms of how much progress you can make on your own or with a small team.