I vaguely remember an old post from here showing someone hacking up Bluetooth to give SBC codec better quality, and it only being available on Linux (or maybe it was Linux+Android?)

I’ll try to dig it up and edit it in here, as I think it was a great hack

Do you mean mSBC?

I found a couple links, since I remembered that Zenwalk distro was one of the first to include it. They call it SBC XQ

[0] http://soundexpert.org/articles/-/blogs/audio-quality-of-sbc...

Via

[1] http://www.zenwalk.org/2019/09/audio-quality-of-sbc-xq-bluet...

Definitely, having just bought some XM4s I was kinda taken aback by having LDAC automatically pop up in my audio settings. Very neat to see support being that seamless!