There are a lot of kiosk projects around, especially for RPi, but their
business models currently make building a community difficult because
what they want to sell is the software image or to tailor the image
to focus on their own web services.
In other words I guess you should think hard about what you are trying
to build a community around! If your business model is based around
selling awesome custom hardware and/or back end web services then you
have have plenty of scope to work with others on the software image.
Perhaps think about working to build the target image using OpenEmbedded
(maybe also the RPB from Linaro but that’s up to you). To some extent
you don’t have to build a community (which can be hard) instead you can
join the OE community.
There’s already some starting bits and pieces:
Although its quite old so adding a core-image-chromium-kiosk would
probably be the first job.