Not just Dell… bought an HP Elite x360 in 2018 and it had to go back twice too; first time because they jammed a physical blocker for non-LTE models into my sim slot (then sent it back after removing it and putting the same blocker back in, afterwards gave me free on-site repair for this issue, fucked up my board during that and came back next day with a replacement board) and second time because the keyboard died after a year. Solid ever since, still running perfectly but these initial issues should not happen with a 2500€ device.
This will help: https://wiki.archlinux.org/title/Dual_boot_with_Windows
Applies to PopOS the same way, except for installation steps involving pacman. I’d revommend going with systemd-boot instead of grub, not sure what Pop ships.