You’re unfortunately right that a Linux phone wouldn’t solve these problems and I’m with you that devs who bend the knee to Google have no interest in providing a Linux phone version - at least for the foreseeable future.
Once there’s a considerable market share for Linux phones (which may never be the case…), those users are potential customers and the tides will shift.
Until then it would at least provide a portable computer that can do a lot of the things current smartphones are capable of, but without the restrictions created by Google and Apple.