I don't know of any e-ink displays outside of Fossil but give Garmin a try. I use the Vivoactive 4 and get a week+ of battery.

I went from Pebble > Fossil > Garmin.

Withings. Small oled display, looks like an analog watch until you use it. Ton of sensors to monitor your health, or none if you don't want that. And a huge battery. Like huge enough to lose the charger between charges 😆

Garmin is know for excellent battery life. I don't think they use e-ink though.

A much bigger drawback (to me at least) they lack Google Pay support and keep pushing Garmin Pay which is not widely supported.

Even more, I get pretty consistently 3 weeks per charge with my fossil hybrid

Another vote for Garmin instinct (2 solar in my case). Not E-ink but oldschool style black/white LCD. Full charge with nightly pulsox is just above 2 weeks, would be 3 if i turned off nightly pulsox. With solar, if you are active outside and have a sunny climate, you probably do not need to charge basically at all.

There is also the instinct crossover for the hybrid look. But first series instincts are supposedly hit or miss on the software. And trust me, the whole analogue watch thing is nice for looks, but really you will not look at it if you have a digital clock on the watch face.

Garmin Instinct has a 30d battery. I've used one for just over a year and it's all I need from a connected watch.

I use the tic pro 5.

Its 3-5 days a but I have everything on and work out every day.

My Coros Pace 2 will go 2+ weeks without a charge if I don't use it much. Don't think it's e-ink and I wouldn't really call it a smart watch. You can get texts and weather but when it syncs with the phone. It's more of a fitness watch.