EinkBro is a browser aimed at, as the name suggests, e-ink devices. That said, it has some really useful features, including a "save as ePub" option.
This not only solves the "format the document for my device", as ePub is a liquid-layout format, but also allows you to combine a number of articles into a single file (you can add more later), which is useful for organising reading by topic, project, or date. And you can read the articles using dedicated e-book software (Kobo, PocketBook Reader, FBReader, or native e-reader apps). I've found that especially useful.
This not only solves the "format the document for my device", as ePub is a liquid-layout format, but also allows you to combine a number of articles into a single file (you can add more later), which is useful for organising reading by topic, project, or date. And you can read the articles using dedicated e-book software (Kobo, PocketBook Reader, FBReader, or native e-reader apps). I've found that especially useful.
More: <https://toot.cat/@dredmorbius/107958709435468728>
(For Android only AFAIU.)
<https://f-droid.org/en/packages/info.plateaukao.einkbro/>