How to move flatpak applications to another drive without needing to launch it via flatpak.

Hi I am using linux mint and I am wondering how to launch flatpak applications from another drive. I need to know how to use the flatpak command to launch their applications from another drive. The drive type I am trying to us is NTFS.

The lack of responses may be due to your question indicating a significant degree of confusion in the question - both in technology and terminology - and missing information, along with an apparent X/Y problem. Rather than try to clarify each detail in turn, I’ll rewrite your question and answer that question. This way you can identify the specific details which differ in your case.

I have Flatpaks installed as system, i.e. in /var/lib/flatpak/, on my laptop running Linux Mint which has all data stored in a single ext4 filesystem mounted on / backed by a single disk. This filesystem is almost full. I have an external disk with a NTFS filesystem containing data which I need to keep there.
How do I install more Flatpaks on this system?

You need to free space in the filesystem mounted on /. Given the size of modern disks, the operating system and applications including Flatpaks, it’s most unlikely that any significant amount of this space is being filled by Flatpaks.
The Linux Mint community is very helpful and will be best able to assist you with an analysis of your storage, freeing space and understanding how to better use is as currently configured and when you build a new system on the same hardware. Be prepared to show the output of various storage commands including df -hT, lsblk, and to see how much storage is used by your Flatpaks, du -hs /var/lib/flatpak/.

Don’t try to move application storage to a NTFS and fuse mount it on /var/lib/flatpak/.

Are you trying to install Flatpak applications on another drive? You can do this with installations, see - Adding a custom installation. But I’m not sure if this works with a NTFS formatted drive.

For various flatpak-commands you’ll need to specify the --installation=<NAME> parameter to pick your installation.

After a new login, the environment should be altered to show all applications from the installations (at least on Fedora & Arch Linux this works by updating the XDG_DATA_DIRS environment variable).