We have been waiting for years to have that typical Yaml feature.
This lets you create variables in your Yaml actions workflows that you can reuse later, including more complex data structures like objects and lists that you can spread into jobs.
TLDR: less duplication, although the syntax is a bit awkward.
I agree the md editing story for non-dev contributor is not great.
You can try a git based CMS like Tina, they have a Docusaurus starter/example.
StackBlitz web publisher is also a good solution, allowing you to run Docusaurus directly in the browser in a very simple interface allowing you to commit or send PRs easily. No need to install nodejs locally, and you get a real preview.
This lets you create variables in your Yaml actions workflows that you can reuse later, including more complex data structures like objects and lists that you can spread into jobs.
TLDR: less duplication, although the syntax is a bit awkward.