Your comic is really young so I can't really determine they type of dark it is storywise yet (so far there is what looks like genocide? and a rebirth of sorts?), although at face value it has a very barren atmosphere. Not "it's unfinished" barren, but apocalyptic or desolate.
I feel like I've been bumping this comic a lot, but out of the stuff I read this one feels like it fits best.
The Dogs on the Railroad - A sort of bittersweet to tragic comic about a couple dogs trying to survive during the apocalypse. The art gives it a desolate feel, that is somewhat similar to yours.
As for other comics, I don't really know how dark a story has to be to qualify, but I have a lot with some dark themes.
Feel free to ignore these since they don't quite fit with what you're looking for, I'm just throwing other darker stories out there in case you would find any interesting. (Sorry I don't have more that fit the topic.)
Sun Rising- A romance-tragedy about a vampire and a human. It has it's cute moments, but the atmosphere is very bleak overall with it's earthy tones.
Ninety-Nine Righteous Men - LGBT+ religious themed horror comic about a boy who gets possessed. I would suggest checking out all of K. M. Claude's work if you like sexual horror.
NINE STONES - Another LGBT+ horror about two kids who fall in love, with murder, torture and gore.
Angels Don't Live Long - A dark slice-of-life comic about two women, featuring some heavy themes.
The Book of Decay - A fantasy about a guard who has to make a difficult journey. This isn't the darkest comic, the atmosphere is actually pretty standard fantasy, but it does center on themes of death and decay.
I myself have a darker comic, but how dark it is varies. Some people find it boring and really easy to read, others find it too dark or depressing. Overall it is a psychological drama that focuses on themes of mental health, trauma and abuse. The story is more slice-of-life/based off life, so it certainly doesn't have the same atmosphere as your work.
