Always publish on your own platform then syndicate it across all the relevant social media providers to get exposure. It's a huge pain, especially now that most platforms are closed and don't provide automation (APIs, RSS), but it's really the most flexible solution. It also makes syndicating to new providers a lot less painful since you'll have some standard raw form (e.g. Markdown) which you can create a manual or…
I hear org-mode is a good alternative. In the mean time, consider storing a permanent .html version upon publication of markdown