Safari reader-mode can be activated on the normal page of the Washington Post when it is loaded half-way. Reader-mode discards the ads, side-bars and other junk anyway. IOW when activating Safari Reader-mode as soon as Safari allows, the AMP pages loose a lot of their benefits. Combined with ad-blocker and a proper image compression probably little benefits remains for the end-user.

Startpage.com delivers the same results google.com does. I've never hit AMP pages, so I assume they neither they redirect to AMP pages, similar to duckduckgo's !g.