I’m guessing it’s not a big deal to replace it with a third party text messaging open source app; I’m not sure about the Dialer, though.
It would be an interesting solution, to port a few mobile Linux apps to Android (some of them are already there) - I’m a bit worried about potential maintenance burden for platform support; but it could benefit KDE/GNOME apps by getting feedback from a bigger bunch of users.
My personal workaround is a smartphone book case with a spot for the debit card.