I second doing it on SN, at least for the first few months to see if you get traction.

I've done blogs with wordpress, blogspot, and medium before, and the biggest problem is always discovery. Hosting your blog on SN gives you a bit of visibility to start with. There are lots of people here who would engage with your posts and perhaps you could enlist them as your marketing force (sharing on nostr, X, reddit, so on) -- you could even offer bounties for sharing.

The easiest, lowest cost way to do it might be to publish in ~bitcoin_beginners and just put a little tag at the beginning of your posts (eg. [FM] is what ended up working for the fiction month contest).

If you really wanted to force yourself to commit to the writing, you could pay for your own territory.

I know that @sox is working on a editor that is going to allow a lot more control over how posts look and there is also the idea that SN territories could one day be hosted at your own custom domain.