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?
Yes, you can just install the apps you want, then remove the ones you don’t, like the browser or app store. Though if you care about updates (app, security) you may want a script that does that for you