After some playing around and thanks to a key hint from Jackie, I’ve figured out a working example, actually 3:
curl -i -X POST localhost:3000/api/v1/replaceAndPlay --data "service=webradio&type=webradio&title=Nova%20La%20Nuit&uri=http://nova-ln.ice.infomaniak.ch/nova-ln-128&albumart=https://www.nova.fr/sites/default/files/2020-06/Nova%20la%20Nuit_1.jpg"
curl -i -X POST localhost:3000/api/v1/replaceAndPlay --data "service=webradio&type=webradio&title=KCRW%20Eclectic%2024&uri=http://media.kcrw.com/pls/kcrwmusic.pls&albumart=https://www.kcrw.com/music/shows/eclectic24/@@images/image/listing-square"
curl -i -X POST localhost:3000/api/v1/replaceAndPlay --data "service=webradio&type=webradio&title=BBC%20Radio%204&uri=http://bbcmedia.ic.llnwd.net/stream/bbcmedia_radio4fm_mf_p&albumart=https://radio-directory.firebaseapp.com/volumio/src/images/radio-thumbnails/BBC%20Radio%204%20FM.jpg"
What is now the best location to keep these scripted commands (bash scripts)? Only /media folder or could /usr/local/bin et similar be a valid and upgrade proof alternative?