https://www.ebay.co.uk/itm/ONEVER-Bl...A/392060259129
According to what you've said you want it to do, that will do the lot. Tune your radio into whatever frequency you select on the device, pair it to your phone, job done! It'll stream music from your phone while navigating, silencing the music while the sat-nav directions go through the speakers, if a call comes in, that takes priority.
At that price it's cheap enough to try and if you don't get on with it, you can put it in a drawer and forget about it - the one i bought is now set up permanently in my Rover so i need another for my Volvo now!
If you get one of those small windscreen suction mounts, it will fit in (i had to add a bit of sound proof sponge to pack it out a little) and you can mount it on your windscreen next to the A-pillar at mouth height, still easy for track control, phone answering etc. This is what i used :
https://www.ebay.co.uk/itm/360-Rotat...d/392095681245
Others are available, have a look and take your pick!
