Oddly enough, the US is almost the only country in the world that allows you to renounce without having another citizenship.I wouldn’t recommend it, bit technically you don’t need another citizenship first.

(Seriously, don’t do this.)

Before going to Flatpak just for newer versions of software, consider APT pinning. You can actually use testing or Sid packages on more stable versions of Debian while still keeping the advantages of Debian-specific packages.