I created a bootable USB drive with Etcher and PopOS image, created a 60 Gb partition for Linux and 8.5 Gb for SWAP in Disk Utility in MacOS, and proceeded to boot into the USB by holding down Option (Alt). Then in the PopOS installer as was needed I made another partition 1Gb for /boot/EFI. Selecting all three of proceeded to install PopOS which installed nicely. Upon restarting and holding down the Option key to boot back into MacOS, only the EFI partition on which the PopOS is shows up (And an old Windows Boot Camp with no OS in it). The original MacOS partition is still on the SSD but I don't know how to mount it (by going into recovery mode I was able to see the 3 partitions but each of them were unmounted). It seems like the problem is with the volume I made for the boot/EFI which the computer is mounting automatically but I'm not sure.
Please let me know how I could boot back into the original MacOS system. Or mount the MacOS EFI partition