There’s an instrumental band called Mushroom Giant whose album Kuru should serve you well.
Also, there’s a one-song album from the 90s called Light of Day, Day of Darkness by a sort of symphonic metal band called Green Carnation…Easy to lose oneself with such a long song playing. There are vocals, but they’re almost irrelevant.
Same goes for the one-song album by Sleep known either as Jerusalem or Dopesmoker in its two different versions. Lyrics are so slow as to be incomprehensible and only enter the song occasionally. However, some people will be energized by the song while others are battered and bruised by it.