A problem is that even within the niche of small phones, not everybody has the same wishes. Compared to your ideal specifications, my wishes are: support for microSD card storage; battery that easily and reliably lasts a full day with moderate phone usage; fingerprint sensor, not necessarily on the power button; camera decent, not necessarily great (I don't care that much about low light performance, for example). I'…
Have you tried KDE Connect? (Hint: It's not only for KDE desktop users.)