I use, depending on mood or circumstances, a SD cars with a dozen GB of MP3, or use Finamp on my phone via Android Auto.

My collection is still made exclusively of MP3, mainly because it’s a large-ish collection of pretty high quality files (mostly LAME V0) with all the tags just right (Picard+beet and a ton of work).

I curated this over the years, it sounds more than good enough on my hardware, and I don’t feel like throwing the whole thing away because something a little fancier came along, especially if in this day and age it still means taking a loss in terms of compatibility.

Both with the car, and with my Yahama network receiver/amplifier. The car is relatively new (2020) the amplifier is a little more seasoned, but it can direct play mp3, while I’d have to transcode opus.

Someone shoot me the day I change HiFi hardware over codecs.

With this being said, I’m not sure I’d transcode Opus into MP3 on purpose.