They really shot themselves in the foot by going straight to phones.
The better way would have been to work on tablets first and working out all the bugs on larger devices with a limited feature set before moving into phones with the attendant issues of regional cell bands and restrictions.
tablets (especially ones that could be flashed with Linux, i.e. not iPads) are way less common than smartphones, so you get fewer devices to choose from for testing, fewer users who can run it, report bugs, and support the project, and less interest in general.
What are the chances of everyone interested in this project already having a tablet? I don't own any, and I certainly wouldn't be going out to buy one just to test running Linux on it. I do have multiple old phones I could turn into development test devices however. Anything is better than nothing.