Yes, you can convert a smartphone into a dumbphone by removing its operating system.
Yes, you can convert a smartphone into a dumbphone by removing its operating system.
You could skip Play Store and browser, just use services instead. Removing the package installer while keeping Play Store might also work as an alternative.
You don’t need to remove all Google services at once. Simply uninstall the Play Store while keeping Google Play Services active for apps that depend on them. But be aware that certain applications might stop functioning without the Play Store installed, even if Google Play Services remain.
I believe you're likely able to do it – the issue is whether your phone supports it. There could be options through ADB that aren't available via the interface, though I'm not entirely clear on how it functions. It seems unlikely you can delete system apps using this method.