You seem to have answered your own question when you've mentioned "I do not want to be dependant on a framework" in the same frame when you say that Carbon disallowing unmanaged code to create instability in the framework which could deteriorate and break hooks of managed plugins, extensions and modules Carbon supports is a "giant middle finger to Harmony devs".
The Harmony support Facepunch added isn't meant to be used the way plugins out in the market are used, just a bundle of patches that change the server code, and if you want to run Carbon or Oxide, you might be out of luck to have a managed and secure environment (speaking of memory modifications of the server). The platform they added is dedicated for frameworks to be built around them, they even have quick start tools on their GitHub where you can create mod loaders using the Harmony system.
All in all, porting it to a Carbon module or a regular plugin will work just fine, just requires a little bit of extra work. Also, we only support Harmony v2 as it's the most performant and most up to date.