So I commute year round in Calgary and that means cold and dark. I can't seem to find a tail light that isn't disposable garbage and will actually hold up to a few years of use.
Yes you can basically buy tail lights in bulk off Amazon - but I hate tossing dead junk in the trash. I would rather pay more for a light that lasts.
My perfect light would use replaceable 18650 (or whatever size) lithium ion cells, or at least have USB-C with pass-through charging (so that I can run it off an external battery in a pinch).
For front lights I use Outbound Lighting and they are perfect - long battery life, great performance, pass-through charging, works in the cold. Unfortunately Outbound doesn't make tail lights. I've begged.
I really like the Garmin varia too, but it’s better described as a great radar with a pretty good light attached to it. Not sure you’d like it though, it’s battery life isn’t great (because it’s running the radar and communicating via ant+/bluetooth.
I just picked up Lezyne KTV drive lights. It’s a pretty good system with decent battery life and flash mode memory. It also has a built in USB A plug so no cables are required. I don’t think there’s any light that meets all your requirements so I think you’re going to have to prioritize.