Bike computer for bike data, including navigation aids. Some bike computers can notify you of calls and texts. Check Bryton, Lezyne and others, besides Garmin, Wahoo, etc. The batteries will last a lot longer.

I use a very basic XOSS G+ that lasts two or three rides per charge, around 12-18 hours depending on whether I use the backlight. No navigation aids, no phone connectivity (other than syncing to Strava after a ride), just basic GPS tracking and some in-ride data -- speed, distance, time, grade.

Bluetooth doodad if you need phone access to take calls, etc. There are earbuds and headsets with touch and/or voice control for that. Friends who run businesses or need to be on call 24/7 use 'em for phone access. But the phone itself stays in a pocket or bag on the bike.

I used to use a convoluted mount and ANT+ adapter with extra power pack for my old iPhone 4s. Wouldn't want to go back to that now, although I still use that rig for my indoor trainer sessions since the ANT+ connectivity is handy for my older sensors. But my outdoor riding bikes are mostly Bluetooth sensors now, although the XOSS G+ and some other computers are compatible with both Bluetooth and ANT+.