Is there an easy way to donate an NFT at the floor / OpenSea bid without realizing the sale?

When you send it you should be realizing a sale at $0 not at floor value.

If it's leaving your hands and you're getting something for it, that's a sale. Maybe I'm misunderstanding what you're trying to do?

Donate it directly to a 501c3 like www.foundationfor.art 
Value at time of donation is deductible for Americans. Under $5k is self reported.

Looks like an opportunity to build OTC for NTFs(if not already available).

Why? Sounds like a terrible option to have.