The camera is too important for me to give up my smart phone, and I don’t want to carry a separate device just for taking photos/video.
Maybe if the came out with a feature phone that had a camera on par with a smartphone and supported syncing to google photos or immich or synology then I’d consider it.
You can get a normal android phone, then hit it in the head with a brick, remove googlr play services, don't add an app store back, and get a minimalist launcher, the end result is what you're looking for, and it becomes hard enough to get a new app on your phone, that its much easier to resist