disclaimer
I’m a Debian user and not a Mullvad user. When installing software, I carefully read instructions and almost never follow them because in most cases I know how to deal with my distro better than developers.
There is a repo for noble, I’ve checked this before writing my answer. It is always possible to edit apt sources config manually and specify any repo you want regardless your distro codename. IDK what is Mint Store, isn’t it about flatpacks that TS doesn’t want to use?
vim