Another point for doom/stoner metal: Samsara Blues Experiment got me through my OS class in college. It's pretty easy to get into too since a most albums are uploaded in full as single videos to youtube. Just beware that one of the big channels uploading videos, Stoned Meadow of Doom, is questionable at best in the scene since operates on a pay-to-play basis.

Otherwise, if you don't mind some harsh vocals I also recommend atmospheric black metal, as well as drone metal. Caladan Brood, Saor, Eldamar, Sunn O))), and Summoning are some of my faves.

Could you clarify that note about Stoned Meadow of Doom? I mentioned them in my sibling comment - I'm not affiliated, have just been enjoying the channel off-and-on for years, so I'm curious.

Riffpedia has a better article[0] then I could write, but the TL;DR is SMoD used to try to do DMCA takedowns against over stoner metal Youtube channels, as well as running a pay-to-play (as in, the bands pay to play) festival for a couple years. The latter being the bigger issue from what I've heard; stoner metal ain't exactly a well paying genre to begin with, the fact the SMoD basically makes money off uploading other peoples albums (he keeps all the ad revenue) and then makes bands pay to play in his festival was widely seen as a "dick move".

[0] https://riffipedia.fandom.com/wiki/Stoned_Meadow_of_Doom

Another second here. There's a YouTube channel with full stoner metal albums (Stoned Meadow of Doom: https://www.youtube.com/channel/UCknVpWR6m2Ijzkqo-aPXs_g ; been around for quite a while, though I have a vague fear of them disappearing due to the obvious copyright infringement...).

As for specific bands (though I don't think on the stoner metal spectrum, but ones I love): Baroness, Sub Rosa, King Woman, Bell Witch, Mastodon.

And for something a bit farther off from metal, but still in the spirit of heavy, nearly ambient - The Kilimanjaro Darkjazz Ensemble (https://www.youtube.com/watch?v=AyORieDhpkg ) / The Mount Fuji Doomjazz Corporation (which is apparently the live version of "The Kilimanjaro...").

Mount Fuji / Kilimanjaro Darkjazz are both great bands, featuring the same members, but being two different projects (hence the difference in sound). You might have a look at Kammerflimmer Kollektief or Nadja, if you're looking for recommendations :)

I second this (most excellent) recommendation and suggest, in particular, the band "Windhand".

For example, Windhand's song "Three Sisters":

https://youtu.be/0FkhnGdwDcw

I would listen to all of Evoken's work while I was programming lol. One day the earbuds had accidentally unplugged and people were looking at me like "HOW CAN THIS MAN FOCUS?!?!?"

A Stoner/Doom playlist isn't complete without Sleep.