I just received $1.00 USD on https://boardwalkcash.com from a giveaway that makeprisms on X was doing.  I was able to send any portion of the USD balance on there to any invoice or Lightning Address.  I verified it by sending $0.50 worth to myself.  Successfully received.  Neat.

It's open-source at https://github.com/MakePrisms/boardwalkcash