And this song which isn't even from armored core but is really good
https://youtu.be/wYhzZN0Mguc?si=sRGuDxVcr3JLy3g0
The song is King's Elliott - lost again (video contains spoilers but this is where I found it)
Ok, I only just realized exactly how good AC6's soundtrack is, and all I can say is... OH MY GOD HOW DID I MISS THESE SONGS WHILE I WAS PLAYING; https://youtube.com/playlist?list=OLAK5uy_lelo0nKJjwCt-aT7lxRwiEd5HwBQmkUzM&si=R6y1oJiDoAu9mq-V