I wonder how hard it would be to open source something similar with something like an nrf52 or similar and a 3d printed enclosure I might have to look into this tbh
Depending on what features you want/need, you can get a used Pebble on eBay and run Rebble on it. More hoops to jump through if you use an iPhone, but android support is pretty straightforward!
Not sure if they are still available, but after pebble shut down, I got this Chinese watch called amazfit bip. It has a color e-ink display and lasts roughly a week on a full charge.
I was able to sync to my phone using FOSS called gadgetbridge so I didn't have to install sketchy Chinese software on my phone.
Man, I've been dying to get one ever since a friend told me about em.
While I can get them via Aliexpress, they come with a very minimal case, with the sides exposed. I'm struggling to find anyone selling replacement cases and I don't have access to a 3d printer to make one myself unfortunately.
I'll keep looking though.