Unfortunately no. Domestic F on its own doesn't get you lounge access unless you buy an RCC membership, and FTL will only get you into LH Business Lounges (there is one at JFK T1, where LH uses a different terminal from UA, but that's all I know of in the US).

Only a SEN or RCC card will get you access.

No lounge at KOA anyway (not that you need one when the terminal is mostly outside anyway, and the weather is amazing (as it usually tends to be!). Enjoy Hawaii!