The problem with these OSS phones (all of them, basically) is that ... what apps do you use?

If I want to buy something on Taobao there's not a single OSS phone that has a Taobao app. If I want to use WeChat to talk to former students, coworkers, friends, and family ... there's no WeChat app.

Having "great tech" only helps if said tech has credible alternatives for things people use all the time. That is the sad power of "network externalities".