Save to ePub from sites such as Archive Today works fine ;-) I've not specifically tried paywalled sites, but so long as you have a subscription I don't see why not.

With two layers of adblock (local LAN, IP-based, adblock on EinkBro itself), I see no ads in saved content, and very rarely in full Web view either. AFAIU it filters the source article through Readability.js, so the main article is what's saved, not navigation, asides, etc.