[asdem1]

It won't go for weeks, but days, and it takes some sideloading and finagling to get certain apk's to work, but I use a Sonim XP3+.

Runs Android Go, big battery that lasts a while, I can use Signal Messenger on it (though not super well), and it's tank-like in its construction. If you want to take that up a notch in terms of build quality, Kyocera sells a similar phone, the Dura XV Extreme+, which is roughly $250.

r/dumbphones is a decent resource. Unsuprisingly, it's not a large community, but it's a good place to get people's anecdotes about specific models.