Second Mihon. It’s an all-in-one downloader and reader, and supports reading offline.

They intentionally removed this feature years ago. It was possible to reenable via a dconf setting for a while but I believe that was also eventually removed.
So annoying.

Valve are a private company, so Microsoft can’t just barge in and buy it up.

Considering the investment Valve has poured into Linux because Gabe doesn’t trust Microsoft enough to have his business rely on Windows, I’d be pretty shocked if he decided to sell up to Microsoft.