OP wrote:
"Santa is bringing me an external SSD for Christmas. With my old drive it would probably be a several hour ordeal to do it that way, but that's my fall back plan."
You haven't told us what you use to PLAY your music.
Also, how do you "keep" your music library?
Example: do you just use iTunes...?
(If so, your music is probably in your "iTunes music folder" in your home folder).
You need to tell us about these things, so that we may make more specific recommendations.
IF it's "just iTunes"
and
IF you keep all your music in the iTunes music folder
then
You could try this:
Copy the iTunes music folder to the external drive.
Connect the external drive to the new Mac.
Open Music.app (is that what it's called, now?) and now "re-import" the music from the old iTunes music folder.
If there's a lot of music, it will take time to import, but it should eventually "digest it all"...