I think you either underestimate your own ability with tech or over estimate the general user. I still get calls from my parents when Firefox updates and a "new box" shows up. This is an extreme example, but this phone could be used by finance or hr team members who are also not expected to really be tech focused.
Just a idea, but support could be a reason to pick a 3rd party to manage these kinds of devices instead of installing the original project. You do open up extra avenues of compromise, but rolling out an OS project you are not really an expert in to staff is a big risk for usability. I can see a value proposition of "locked down devices, more secure than stock, 98% as secure as possible, 24/7 support" being an attractive tradeoff for some companies or people.
