Dikaios1517 on Nostr: Upload the flier to something like nostr.build and link to it in a Nostr note, such ...

Upload the flier to something like nostr.build and link to it in a Nostr note, such as a kind 1, or the long-form docs you are creating. Long-form on Nostr is all markdown, so you are not limited by the long-form clients for text editing and styling; you are limited by what can be done in markdown, and it requires a bit of learning to know how to get things to render the way you want them to.

Laeserin (npub1m4n…c2jl) may have some other options. I know she and the other folks behind #Alexandria are also using asciidoc notes, instead of markdown. I am not familiar with asciidoc, but it might offer more options for editing and styling than markdown. That said, markdown does support creating a table of contents for your document. I have not tried adding one in any Nostr long-form client, though, to confirm if it works.