I am personally looking for the exact opposite. Read my newsletter subscriptions in my rss reader, so that I can choose the time I read them and keep email for important stuff.
I do that, with emails. Simply thanks to notmuch-emacs my feeds does not arrive in my inbox but in a dedicated dir and I can access it from notmuch simply hitting 'r', outside notmuch, i.e. on mobile I can simply access that dir in my IMAP taxonomy with K9 as MUA.
In the past I keep them separated but manage them, especially store&search with full-post locally saved in case it disappear from their origin it was hard or ineffective.
