it will connect to my home wifi, but says there's no internet.
Not all Wi-Fi offers internet. But that would be unusual for home networks.
Try restarting the Apple TV box and the router/access point/other network gear. If you have Wi-Fi repeaters, or mesh satellites, then one of this might be causing issues for nearby devices. Restart those as well.
Everything else in the house works on the wifi, even other wifi devices, but not my Apple TV.
Maybe there is local interference, that makes connectivity harder for the exact location where the Apple TV box is?
Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support
If you have a computer with Wi-Fi that can be used ethernet-connected, then that can be used as a Wi-Fi repeater on its own network name (Internet sharing). Might be useful in an emergency, but setting it up for the first time could turn out to be a project on its own.
I'm pretty sure it's about that time to replace it,
“Apple TV HD, tvOS 15” would be current. It is not the most modern model, but good for what it does and fully supported. If this is about a different model, then please specify. Identify your Apple TV model - Apple Support
but I'm kind of curious if there's any suggestions anyone could make for what else I might be able to do.
While intended for emergencies like a botched update, you can restore through a computer. It would erase to factory settings and get the latest update, but that shouldn’t be much of an objection if it is not working now. Restore your Apple TV - Apple Support.
Or if I could even trade it in somewhere towards a new Apple TV.
Apple TV (any model) is not eligible for trade-in through Apple. You’ll have to check the second hand market for a monetary compensation.
