I use pinboard for my "read it later" functionality, but I'd switch to Instapaper if it could deliver to my Kindle account (I don't use a Kindle, but do use the

I use pinboard for my "read it later" functionality, but I'd switch to Instapaper if it could deliver to my Kindle account (I don't use a Kindle, but do use the software on my iPad). I'm assuming it's an Amazon limitation that means auto-delivery only works on the Kindle hardware, no?