I use Zotero for this. Used to use it as purely a reference manager for scientific papers, but started storing all kinds of stuff for archiving or later reading. My workflow is getting all news/articles I might want to read from RSS, and add to Zotero what I want to keep.
With the browser plugin you can store snapshots as well, so you can preserve it if it changes or is taken down. Not sure how a mobile experience would be as I only filter RSS-items on my phone, but no reading.
You can use file sync through a paid subscription or use youe own WebDAV server for it (I will be moving to this). Other than that, it is a database and folder with files, so you can probably use SyncThing or store it directly in Nextcloud also I would think.
I am a folder-person, but it also supports tags so you have flexibility in how you organize.