I always wondered why they didn't try a tablet first. Like the Chromebooks, but in tablet form, heavy on Firefox branding. Maybe this too is something that would've been an 'also-ran' or market failure, but I still want one even as I type this.
Chromebooks already run Linux when so coerced, and are the most bulletproof computing platform for education and business. What could be special about the FirefoxBook?
Perhaps, instead of expending that much effort to engineer a new tablet entirely from scratch, find an Android tablet and put a Mozilla sticker on it.
With a tablet I would at least have a good browser, which would cover most of my idle browsing. And if there is something I absolutely must do on Android then worst case is I pull out my phone and use that instead.
The web -- though not Google's non-standard Chrome apps through the browser, as yet -- works quite well on Android.
I signed up for the contribution program, received a tablet, built and ran updates on it, participated in Discourse discussions and wanted to do more. Sadly, builds started breaking, they weren't attended to, and the program died a slow death.