How does this work?
I am using feed2toot to process my RSS feed and publish new posts to Mastodon. To not spam Mastodon with old articles, I have added old posts to the feed2toot cache.
The POSSE IndieWeb website has you covered: The basic idea is to post your thoughts on your own site and then publish copies of it together with links back to your site on e.g. social media. It's cross-posting at the end but with your own site as the single source. The benefit is that you still have your content if a third party platform is no more or you don't want to use it anymore.
What about a "posts elsewhere"?
"Posts elsewhere" is supposed to be a section usually under a blog post which lists the distributed copies or references, e.g. on the Fediverse, where readers can go and interact with.
Something I am going to look into for sure but let's start with posting to Mastodon first.
About the author
Jan Beilicke is a long-time IT professional and full-time nerd. Open source enthusiast, advocating security and privacy. Sees the cloud as other people's computers. Find him on Mastodon.