Thanks for the recommendation, will give that a further look.
I have played with Pinchflat as mentioned by another poster. I’ve found that some of the ones that aren’t on YouTube, you can use AudioBookShelf or similar in conjunction with a vpn set to a non core country for the podcast, you can either remove or at least greatly reduce the ad inserts.
Have an experiment with that, I use a gluetun docker and link my ABS docker to that.
Here’s mine from Accubattery, running Graphene on Pixel 8 Pro
Its certainly doable, you just need to decide on where you want to start as a minimum viable product and tinker along as you go but ideally think far enough ahead about ideal situation so you don’t paint yourself into a corner and have to restart from scratch to get a certain outcome, although the Pi is pretty flexible for the power you’ll need.
I did this around 20 years ago (obviously not with a Pi back then) but as things changed I came round to the less hassle option of a phone and Bluetooth, particularly as I was often driving cars I couldn’t tinker with too much.
I had an implementation with a fold out 1 DIN touch screen which replaced the stereo and handled audio amplification etc and one with a stand alone hot plug 7" touchscreen. I had a reserve battery so that it stayed powered up for a short period of time after parking at home to do playlist and podcast synchronisation to my server in the house.
As other people have mentioned I was using Kodi and running audio from it as well as satnav etc. Mp3car was a good resource at the time.
If you expect it to be flaky you could get one of those old school mechanical time switches with the clicky pegs (or a more modern digital equivalent) and just have it set to power down for 1 click, normally 15 mins, at 4am or whenever suits you - minimally technically complicated and guaranteed stability through planned instability!