You hit the problem right on the head there. Apple have moved away from iTunes to subscriptions to online streaming. Not investing time\money in improving iTunes any more.
I wish you luck in getting a solution. Apple lock things down quite hard, and it is expensive to stick things in the Apple store that leads to less options.
I’ll say this quietly, but there was a point in the last few years I have considered owning an iPhone. But then I looked at the music side and it shocked me as to how closed the options are. You know my experiences from that long thread last year: iPhone music apps - playing YOUR music on the move
Here is a random tangent of a suggestion… carry two phones. Get a cheap Android without a SIM and treat it like an iPod. Plenty of musical options on Android.
Remember how small and convenient an iPod used to be? Now that was the pinnacle of Apple understanding music on the move. 
