Regardless of the distribution, would it be possible to have a phone that can be simplified to include only the features you want? For example, I would only want a calendar, notes, a calculator, calls and messages. I wouldn’t want a browser, an app store or any other way to easily install them. Is this possible on a Linux mobile distro? Does it require a lot of work, like making a specific distro for it?

Linux feels like a great option for this because it can leave enough freedom to dumb down what you don’t need while also keeping a big level of customization, not everyone needs are the same regarding to dumbphones