What some people do is put the home directory on a different partition of the drive. Then you can change or update the OS without affecting home. It may take a bit more drive space and take longer to mount a separate partition when you boot.

if you're planning on changing distros you most probably will redo most of the stuff. you are right to think that backing up your home and /etc folders would be the first thing you should do. you can also get a list of your installed packages so you can reinstall your applications with a sort of checklist. i'm not familiar with popos so i can't help you with that process, but it shouldn't be that complicated.

Well apart from everything other's have said, do not blindly copy everything from one /etc to another. This will cause problems. And yeah, you also do need to have a backup of home, because you have just one partition with everything on it. Also, when installing Debian make sure to check the box enabling proprietary firmware if you need it. Debian also specifies repositories for non-free software, so you'll have to set those if you want to play on Steam and/or have Discord.

Thanks for all the tips. I am going to copy my home directory and some of the /etc files that I have modified to another drive. I also made a list of apps and packages that I need to indtall. I am going to install debian and hope that everything goes right and that I didn't miss anything.

Can you afford a new disk? If so, bam, you have an instant backup. Install a new OS and copy over files as needed.