With gps actively going(most battery intense thing you can do), a forerunner with MIP will last you like 3 to 5 days straight. OLED probably a solid 2 to 3 days straight.
If you just want to wear it when not using it for activities, you get like 2 weeks before charges.
Garmin Venu 1, 2, or even one of the newer Vivoactives would be great. You can get a Venu 2 for probably about $100-$130 on Facebook Marketplace right now. You can also get one of the older Garmin Forerunners for about the same price as well, if not a little cheaper
if he is working a lot in the rain, get him something with more than 2 buttons so he would be able to use the watch using only the buttons (without the touchsreen) if he needs to, something like a forerunner, or instinct (doesnt have a touch screen) or a fenix (but a fenix is one of the more expensive ones)
sublimatingin606
