I'm still fuzzy on what and how they are used in relation to Bitcoin

No!!!!!!

My wallet only accepts btc

It's like how I imagined LNDhub should be... with privacy and being built out into dozens of clients. Gotta love it

Anytime you think you’ve got the Bitcoin network figured…they toss cashu nuts in your face.

In the docs Cashu is described as layer 2, but since it relies so heavily on LN, isn't it a layer 3 ?