For me: Maps and WhatsApp.

I could probably ditch Maps (by using my spouse's when needed, not sure if that counts...), but I have family abroad and other family here), and kid photos to send etc etc. It's true I could do most of that via email, but the rest of the family is on WhatsApp and I would genuinely feel more disconnected from them then I already do.

You can install whatsapp on a virtual android machine on your desktop/laptop. I did that for a while and used a dumb phone (new nokia 8110) as my main phone and hotspot for a while. I kind of enjoyed it, but a couple of things made me give up for now.: First, abysmally bad battery life when using it as a hotspot (and no auto wifi disable when no devices connected). Second, laughably slow charging. Like, not even net charging when using lots of data via wifi hotspot and even in best case something like 4 hours to charge from empty to full. I am still keen to buy a dumb phone that fixes these.

I thought WhatsApp needed to verify the device using a phone number? Does that work with the virtual Android?

I got a simple CAT-model that runs KaiOS.

It sort of supports Maps, but is inconvenient enough to kill the temptation to use it for everything.

As an added bonus, it's water proof, doesn't crack when dropped and the battery lasts a week.

I think music/podcasts would be a big sacrifice for me. I suppose I could do a dedicated MP3 player for music, but especially with podcasts the live-updating feed is something I really enjoy.

You could host this and couple it with whatever would be a good client/player for you: https://github.com/airsonic-advanced/airsonic-advanced