Well if you save the opus or aac it's only single lossy compression, not double unless the uploader used a lossy file as their input. But if that was the case, ripping mp3 would be triple lossy compression...

Any official uploads from recent years are going to be just fine. And if not then maybe their spotify upload is broken too

For mp3 sure, but for opus standards 160kbps is great. I read that 128kbps is generally considered the most you need but 160kbps smooths over any artifacts, assuming the source file doesn't have them.

Well I've used spotify with and without headphones on popular phones, I can't tell the difference from youtube. I usually download the music directly from the original uploader.