...
ssl_certificate /path/to/my/cert.pem;
ssl_certificate_key "store:pkcs11:token=YubiHSM;object=new_privkey";
...

2025/08/08 19:25:30 [emerg] 160008#160008: cannot load certificate key "store:pkcs11:token=YubiHSM;object=test_privkey": OSSL_STORE_open() failed (SSL: error:80000002:system library::No such file or directory:calling stat(pkcs11:token=YubiHSM;object=test_privkey) error:1608010C:STORE routines::unsupported:No store loader found. For standard store loaders you need at least one of the default or base providers available. Did you forget to load them? Info: Global default library context, Scheme (pkcs11 : 0), Properties (<null>))