Awkward sentence, need help with verbiage or if there is a better way to word it.

"However, no details or explanation was provided."

Should it read "However, no details or explanation were provided."

Should it be "nor" instead of "or".

It's been a long time since 9th grade English ...

You need to look up the meaning of 'verbiage'. Your sentence is hardly excessively lengthy or overly technical speech.

Whether you use 'neither' or 'no' or 'not' with the first noun/pronoun, the following conjunction is 'nor' not 'or'.

With 'either…or' and 'neither…nor' constructions, the verb agrees with the noun in closest proximity.

SO:

"However, no details nor explanation was provided."

HOWEVER:
Where there is one noun in the plural and the other is singular, the convention is to place the plural noun last:

"However, no explanation nor details were provided."