A touchscreen notebook with a GSM/LTE modem and a decent microphone running Linux is the closest you can get today as far as I know
while there are android phones that are supported by custom rom's up to ~5 years (exceptions even longer), the majority isn't.
meanwhile a 5year old iphone se is seamlessly supported by the manufacturer and probably will be for a few years to come.
A touchscreen notebook with a GSM/LTE modem and a decent microphone running Linux is the closest you can get today as far as I know