Finally ready to switch my final windows device over to linux, but I'm running into a problem. NTFS drives aren't a good idea under Linux, but my 4 NTFS drives are this full. I own zero extra hard drives, and do not want to spend $300 on another one. 
How can I bring these files into Bazzite WITHOUT just wiping everything and re-downloading 10+ terabytes of movies, shows, music, games, and other data I refuse to delete?
This is a very good idea (and my personal practice). It allows you to replace the OS without touching your personal files. Only reason I didn't suggest it is it looked like available space was already very limited.
It is certainly possible to use Btrfs subvolumes instead of a separate partition, but many Linux distro GUI installers do not have robust support for this and will prevent you from using the same partition for different mountpoints (they typically don't understand or provide a way to set the btrfs-specific
subvol=mount option). On a manual distribution like Arch or Gentoo this isn't a problem at all, but I've had to get creative when using GUI installers for Debian and Solus. Fedora's GUI installer "supports" it, but last time I did it, it triggered another bug in the process later on based on a similar assumption.It is easy enough to do post-install (turning /home into a subvolume and adding it to fstab), but you will still have a hard time later on replacing only the OS, which is the main point of setting things up like this.
If people are willing to read a bit the archwiki install section on setting up LVM is very good and I used to use it to teach newbies when I worked as a sysadmin.