Some Help With Phone Control?

I was gifted a Samsung S9 phone a few months back. I've never used a vehicle-mounted GPS or map device in the past and it was given me to use with a Cardo intercom. The Cardo would only work with the phone over bluetooth, and not with music/general audio, so I bought myself a Sena SMH5 intercom unit.

I'm really pleased with the intercom, the music plays very well (started doing an air guitar jig to "Blue Hotel" around the lounge after setting it up, much to the Mrs' amusement!) and it says it is connected for phone and general audio.

The problem is, I don't know how to switch between my GPS/map app (OsmAnd+) and the music on the phone. I'll do some trial & error if ness, but it would be nice to know how it's supposed to be done, proper, like

Do I simply start the toons (don't even know if it will play a folder of music or not) and then start OsmAnd+ and it will interrupt the music with any directions in SatNav mode? That would be the ideal, I guess. The SMH5 also has voice control so perhaps I can swap around with commands?

Please only reply if you have these devices and know what they can do, thanks, as I wasted a lot of time trying to get things working with the Cardo unit that people said worked with it, but turned out to be wrong. Ta.