I'm picking up this thread as the site I'm currently working on needs to do two things mentioned here. @clarkwinkelmann 's SSO plugin achieves some of the functionality but I'd like to ask the community how they might solve this problem, to see if Flarum is even a viable option for me.
The main thing is that I need for content aspects of WordPress to run alongside Flarum. For this reason, simply injecting block sections of HTML into using existing header/footer sections via Flarum plugins feels underpowered. The WordPress loop would need to run, for instance, in order to access custom post types and titles. A post in another topic here mentioned that running Flarum in an iFrame within another site is dangerous, but it feels like it may be the only way. I've built some version of the functionality I need for most of the site (or can solve them via WP plugins), and am basically looking at Flarum as a prettier/faster upgrade over BBPress, which runs the existing forum. And sucks, frankly, especially compared to Flarum.
Has anyone here achieved anything similar to the level of integration proposed in this drawing?