Good news: I finally successfully upgraded my BIOS from 3.04, and it fixed the suspend issue for me! After some back and forth with support they suggested I try upgrading to 3.06 first, and I did so using the EFI shell updater here. That already fixed the suspend issue for me but YOLO, computer luck is in the air today, and I tried updating to 3.08 and it also worked using the EFI shell updater from this thread! Now my BIOS is fully up to date and suspend seems to be working great. Woohoo!
EDIT: wanted to note that the 3.08 shell updater did not work for me on battery power, but worked when I plugged in.