I think you don't need to run a full node just to transfer them to your ledger nano.
Electrum is enough to transfer and sweep them in your Ledger nano but your problem is you can't able to verify the signature?

If the gpgsuite doesn't work in Mojave you can try other software to verify the signature.

Try this GnuPG

- https://bitcointalk.org/index.php?topic=5105901.msg49695453#msg49695453