"It's open" is not and has never been an effective selling point for consumer products, and it seems that you're effectively trying to sell these things to consumers. "It's open and is better is," and in my experience that rarely exists (again, for consumer products). If it is as easy as you posit (and this isn't my field, I know a little about CPUs and GPUs but mobile isn't really relevant to me), then what's stopping a company with significant talent and cash reserves can appropriate the same approaches and lap you with their closed tech? I don't see how you're not going to have to offer an inferior good at superior-good prices.

Technically speaking, if anything, phones strike me as a harder place to enter, due to the limitations on power budget and the significant premium on marginal performance. I'm not saying it can't be built--I'm saying, who would both want it and not benefit from business-as-usual, closed development?