As the saying goes, the advice I am giving is worth approximately what you are paying for it. Go for a top end cycling computer geared towards endurance events or touring. For me that’s a Garmin 1040 Solar, amazing device perfectly suited for touring and bike packing. Features listed is extensive and easily researched. If you want maps then go maps but they are not even close in functionality or usefulness. Phones are designed to be phones not cycling navigation computers and suck when they are used that way.