What word best means "the state of being an expert"?

Consider "expertise."

expertise: expert advise or opinion; skill or knowledge in a particular area

"But in the absence of such an actual expert, I have learned that the above is a losing battle. I am being dragged, kicking and screaming, into widget expertise."

Alternately, "expertism" might also work for what you're looking for.

For the exact case you specify, being a "widget guru" or guru-dom is used a lot.

Try

I am being dragged, kicking and screaming, into widgetary omniscience.

(I have a cat called Widget, so I consider myself something of an expert on those grounds alone. :-)

I think maybe you want an authority. Because their opinion is authoritative.

able to be trusted as being accurate or true; reliable.

If it is meant to be funny/sarcastic then I would go with master/kingdom.

You can also consider bravura which is a bit of a funny word and would probably only be used in jest for everyday dialogue.

great skill, enthusiasm, and confidence

A person who is an expert is accomplished in their field of expertise. Less used is the term au fait or fully informed; in touch or expert