I recently set up Sonarr and Radarr on my home server and I'm loving it.
However, I don't get why you would ever use Lidarr. Why would you ever download music using torrents? You can use tools like spotdl and yt-dlp to download songs from YouTube music and Spotify, it's faster and more reliable; I have had some issues finding torrents of music from less-known artists.
To me it seems like it would be much better to have a tool like Lidarr or have support in Jellyseerr to download music from common streaming services.
I still burn CDs... my ancient vehicle has a multi-disc changer and doesn't require my phone to be on, so I like having the best quality I can get before I do the burning.
Anyway, for $10-20 you can get any ol' used car stereo from a junk yard that'll work and have a 3.5mm aux port. You can even find some with USB and grab a dirt cheap 32GB nub/stick from Microcenter or wherever.
After the initial setup, it'll be easier and cheaper in the long run than buying CDs. Less wasteful, too. Plus, nobody's gonna see a CD booklet and think they might be valuable and break into your car. Assuming you keep them in there.
I've even seen USB stick mini booklets if you wanna load a bunch up with FLACs if your car system can tell the difference while cruisin'...