TLDR: POSSE: Publish (on your) Own Site, Syndicate Elsewhere.
Is there a guide for how to do the “syndicate elsewhere” part? For the HN audience, the first part is trivially easy (getting a domain, publishing on it) but the second probably isn’t obvious.
Substack really wants you to use them as a primary publisher so they don’t make it easy to programmatically put content up. Other platforms have varying levels of ease around this.