I have my disks set to mount at start up, however I still always have to look for my drives everytime I open up steam or Lutris

I don't really know what to do at this point.

Steam needs to be set to favor the external drive, rather than the local directory - Within the Storage settings, click the three dots next to your external drive and select "Make Default ".

Would this also apply to Lutris and Heroic?

Are Steam and Lutris installed as Flatpak or .deb/APT Version? If they are Flatpaks, I would suggest to try the .deb Versions.

Yeah, they're all deb/apt

What format is the external drive in?

its ext4