For wider adoption, your best bet is probably to pare down WordPress a tad and see what you can make of it. I know David Shanske has a starter version of Underscores with microformats in it already. I think a large portion of the micro.blog crowd that has gone IndieWeb are using it as their CMS of choice.
The other interesting platform to look at is WithKnown which was built from scratch with IndieWeb specifically in mind.
For adopt-a-bility and reach, you could also look at building things like webmentions into projects like Mastodon which already has some IndieWeb pieces built into it.
You could also try asking in the IndieWeb chat at https:/
Here's a rough chart that may give you some useful ideas too: https:/