FrogRadio for macOS as of version 1.7.8 can import m3u files that contain multiple stations. The m3u file may contain various data for each station in the following format:
#EXTINF:-1,Station Name
#EXTIMG:https://station.com/icon.png
#EXTWEB:https://station.com
https://station.com/jazz
#EXTINF lists the station's name. #EXTIMG is the icon image for the station. #EXTWEB is the website for the station. The last line is the actual URL for the station's audio stream. Only #EXTINF and the last line with the stream are required.
When importing an m3u file, you can set the name of the folder the stations will go into. Also, the stream URL can be a local file if specified like file:///song.mp3. A folder in FrogRadio can be turned into a playlist by right clicking on the folder name. If a folder is a playlist all the songs in the lists will be played; the next one starting when the previous one ends. This implies that the streams are mp3 audio files, not infinite radio streams.
Note also, that the imported m3u file itself can be a remote URL of the form https://host.com/stations.m3u or a local file of the form file:///Users/username/Desktop/stations.m3u.