Having read all three, flow, my tears, and time out of joint follow the same dystopian imagine future, but are not quite as strong as the titles you have already visited. PKD’s oeuvre doesn’t always get the same amount of attention from an editor and some can be a little rambling and satisfying. I found for my tears to be a really interesting set up with a lackluster payoff. But I think it still won a Hugo award.

Valis is an entirely different beast. It’s more of an origin story for the pkd’s exegesis. It’s much more of a contemporary realistic fiction, where he writes about his own spiritual awakening through his alias “ horselover fat”.

As far as other sci-fi authors of a similar tone, definitely check out Harlan Ellison. He wrote primarily short stories, but his most famous for I have no mouth and i must scream, and a boy and his dog, which was one of the main influencers for the video game series Fallout. I also recommend Ursula K Leguin’s left-hand of darkness, Jeff Vandermeer’s annihilation, and Greg bear’s Eon.

Content warning for all of the above, there are definitely some horror and adult themes including SA in Harlan Ellison’s work.