My Aurender streamer will stream my stored files with out internet, it uses an apple tablet to control it via bluetooth/wifi.
I'd imagine most streamers that can interface with a hard drive/NAS can also do the same. most phones connect through wifi/Bluetooth regardless if there is internet connection or not. I'm sure there is exceptions but i cannot see why you would need internet to interface with a NAS other then for things like roon or other software that adds meta data etc from the net.