OT? move os and app from HD to usb

[Dave Stevens]

I have a working mint hard drive (spinning) with an app that I want to
move, mint and app together, to a usb stick. I have both and have
looked for info on doing this but have seen conflicting and sometimes
mistaken advice given.

Can anyone please refer me to working instructions?

The source partition is ext3 of 42 GB, 20 in use, target USB is 32 GB
FAT32, can be reformatted ok, no useful data on it. The object is to
have a working bootable clone of the HD setup on the stick.

Dave