it sounds like the bootloader is installed; but not updated to point to the ramdisk and i’d be surprised if your ramdisk doesn’t need a new driver to load the nvme drive since it was created using your old ssd.
also: i’m going to assume that you want 500gb instead of 256gb and i think dd is likely going to give you 256gb since it also copies free space and your drives are not identical; if none of the resizefs commands work, then you’ll be stuck at 256gb. in your shoes i would use that live distribution to create that partition (or better yet an lvm) like you already did; copy the data that you want with something like rsync; install grub and allow that bootloader installation to create a new ramdisk for you.
this way you’re guaranteed to get all 500gb; the bootloader and ramdisk have the necessary bits to run your nvme and installation; plus, if you go with lvm, you’re future proofed since you can add drives to that lvm into perpetuity with each new drive increasing its size or retire old drives without having to remove/re-create the volume and all without having to do any of it again.