2008 sedan non-premium (didn't want sunroof) so I don't have bluetooth. I've been using XM/Sirius for years but finally got tired of it and want to use spotify in the car.

I have an RCA to 3.5mm headphone cable and it works, but sound quality is pretty bad.

What's my best option for decent audio quality? I have a Pixel 3a. USB-C to RCA? Or bluetooth adapter? If I do bluetooth should I use RCA or FM transmitter? Prefer as little clutter as possible. I don't mind using a cable since my interior is black, I'll tape it neatly with electrical tape. I don't care about phone integration since I rarely answer calls/text when I'm driving. This will mostly be for road trips, I'm OK with radio or CDs around town.