Fiction reading stagnant – any recommendations for similar authors to Stephen King?

Potential Dark Tower/Warframe Spoilers Ahead! ⚠️

For context, I'm autistic and have had a love/hate relationship with fiction my whole life. I used to read exclusively non-fiction for the most part and loved some subjects in school because of simply studying them in depth on my own, absorbed in a well-written textbook (at the end of elementary school it was college textbooks on human evolution that I would study for a young scholars program, and in college music theory and orchestration was always one of my favorite subjects). I also really like autobiographies and memoirs – I've read a few memoirs by autistic authors like John Elder Robison (Look Me in the Eye), Daniel Tammet (Born on a Blue Day), some musicians like Pete Townshend (Behind Blue Eyes), Sting (Broken Music), authors' memoirs/autobiographies like Stephen King's On Writing, and even some biographies like Alexander Poznansky's Tchaikovsky: Through Others' Eyes (I'm listening to Tchaikovsky's 4th Symphony as I write this, lol).

I love playing video games and some of the deeper lore in those games, but unfortunately some of my favorite games don't have a dedicated fictional novel series adaptation (like Warframe). I went ahead and put a spoiler tag on this post, because of similar elements I've discovered between The Dark Tower and Warframe, namely:

Dark Science Fantasy elements and some trans realism (science fiction with some magic systems in place and a tinge of horror-like elements, while also having something to do with real life) – portals and gateways between dimensions across space and time (Albrecht Entrati's work on going back to the year 1999 in the Origin System, and the home system of the Orokin that was bridged to ours by the Void when the Zariman Ten-0 got lost in a Void Storm, vs. Roland the Gunslinger's "All-World" and the doorways that lead between Keystone Earth and his world, as well as the transit center in New York City that reminds me a lot of the Zariman/Dormizone between the Origin System and Duviri);

Roland's and his Ka-tet's quest to go back to Maine in 1999 to prevent Stephen King from getting killed in that van accident that happened irl (I don't know why Dr. Entrati went back to 1999 in Warframe yet, but it has to do with "Y2K" – that much I do know);

The concept of "twinners" (introduced in one of the Dark Tower Multi-Verse tie-in novels, The Talisman), and how similar the Operator/Drifter concept is to that.

I'm sure there are more that I can't think of at the moment, but you should get the gist of it. That's kind of what I'm looking for, even if it's not a 4,700 page series, but just one large novel, or whatever.

I also struggle with ADHD (with which I was diagnosed only a couple of years ago, whereas I was diagnosed with PDD-NOS when I was about 6 or 7), and I suspect this has to do with difficulties with just sitting down and reading a work of fiction. The Dark Tower is one of the VERY RARE exceptions to this (especially books 5-7), and it became an absolute page turner for me. I've been trying to read H.P. Lovecraft's work lately because of Stephen King's own admiration for the guy ("H.P. Lovecraft has yet to be surpassed as the twentieth century's greatest practitioner of the classic horror tale."), but aside from "The Call of Cthulhu" and a handful of other short stories that I actually managed to finish, I just can't get into him that much. 🤷‍♂️

Anyways, after all of this longwinded description of my tastes, struggles, and a few spoilers, what are some recommendations you guys might have for me? I appreciate any and all input!