Software Manger should ask what drive to install

[Sandman192]

Have Software Manger ask what drive you want to install apps other then the main drive

[billyswong]

The filesystem structure of Linux Mint doesn't let "system packages" be installed in arbitrary locations. Most other Linux distributions don't either.

If you want software to not use up the system drive space, you shall either buy a bigger drive, or let the system partition be bigger. Or if your concern is those Flatpak software, move the content of /var/lib/flatpak to your new drive or partition then setup mount point to point that folder to there.

[billyswong]

Aside from using mount point directly, one may also use symbolic links to map folders in system drive into corresponding folders in secondary drive, so that multiple mappings can share the same partition space.

[Secret-chest]

You can, of course, hold executables in any location, but you need to add it to PATH. However, the package management system, APT, can only install packages in the standard locations, so it can keep track of it.

[Secret-chest]

Also, in Linux, there are no drive letters, other partitions are just mounted to a point in the root filesystem. There can only be one /.

[cplittlfield]

Have Software Manger ask what drive you want to install apps other then the main drive

Linux and Windows are very different operating systems, and it is a better approach to embrace each one for what it is, instead of expecting them to be clones of each other. Treat learning how to do things in a new way as an adventure. You might end up preferring the different behavior.