Store packages on a USB stick?

I was wondering if I could get the apt package manager to store packages on my USB drive?
I have installed ubuntu mate 20.04 on my raspberry pi 4. Can I do that?

Hi Jackorsomething, welcome to UMcommunity.

Not sure what you need, I think you ask if you can download any apt package and store in usb? Sure,
sudo apt download nameofpackage

This store it in your user folder by default. So you can move them to your usb drive and install .deb packages with dpkg - i or gdebi.

Also when you use apt-get, packages store in /var/cache/apt/archives. But do not remove with sudo apt clean if you want to preserve them for later purposes.

Lucky