NEW YORK — It doesn’t take a genius to deduce that anyone who rants in New York’s Madison Square Park about “Ratatouille” not getting enough respect or gets into a shouting match on 42nd Street about Denzel Washington’s stage credits might have a complicated relationship with the entertainment industry.

For five seasons of “Billy on the Street,” Billy Eichner was a hysterical roving commenter on Hollywood, proclaiming his tastes to any passerby he could corral with exaggerated disdain for those who dared to disagree with him and underlining fury with himself for caring so much.

“Show business, I was always so enamored and so infatuated with it. I was really intoxicated by it,” says Eichner, who grew up in Queens with middle-class parents who encouraged his passion. “I love great acting. I love the movies that I love. And, yes, ‘Billy on the Street’ was a way of poking fun at my own obsession with the entertainment industry.”

But as much as “Billy on the Street” seemed like Eichner as himself out in the real world of midtown Manhattan, his new movie , “Bros” (in theaters Sept. 30), is a far clearer picture of who Eichner is as a comedian, actor, screenwriter and gay man. And this fall movie season, it also happens to be a landmark comedy.

Eichner stars in and wrote the Universal Pictures release with director Nicholas Stoller. (Judd Apatow produces.) The initial germ was to go further with a “Billy on the Street” sketch where Eichner acted as a Jets jersey-wearing sports bro with Jason Sudeikis. But as it developed, “Bros” grew in a different direction. In the classic format of an adult, R-rated rom-com, Eichner depicts an uncommonly honest and insightful portrait of life as a single gay man.

Like “Billy on the Street,” it’s frequently laugh-out-loud funny and packed with keen observations about Hollywood — a Hollywood where, until now, a film like “Bros” was essentially an impossibility. “Bros” is the first gay rom-com from a major studio, and the first studio film of any genre both written by and starring an openly gay man. The cast is almost entirely LGBTQ.

“The history of it is thrilling. It really is a monumental moment,” Eichner said in a recent interview. “I’ve been an openly gay actor and comedian my whole career, way before people knew me. I always wanted to be really successful, but I wanted it to be on my own terms, meaning as an openly gay person. That’s not something that’s easy to do. And that’s true of every single cast member of this movie.”

“Bros,” which will premiere at the Toronto Film Festival, follows Bobby Lieber (Eichner) through modern issues of Tinder dating and monogamy struggles but also makes room for dialogue about how gay lives are depicted in film, and who gets to tell LGBTQ stories. Eichner plays the director of an LGBTQ museum in the film; history is very much on the movie’s mind. Topics include “Bohemian Rhapsody,” a pseudo “Brokeback Mountain” (“The Treasure Within”), a gay slur remembered from “The Hangover” and whether Lieber’s biopic would star Benedict Cumberbatch.

“It’s always been so funny to me as a gay person in Hollywood because, behind the scenes, it’s really not so liberal,” says Eichner. “It was never as progressive as it claimed to be. Just because you claim to be gay friendly or vote for a Democrat or say you’re for marriage equality, that was never really reflected in the actual work that Hollywood was producing. When it came to what they were accountable and responsible for, they never gave us opportunities.

“And on the rare occasions when you did see LGBTQ characters front and center in a film or TV show, the vast majority of those roles were played by straight actors or actors who were not out of the closet, perhaps,” adds Eichner.

Eichner, who co-stared with Julie Klausner in the series “Difficult People” and voiced Timon in 2019’s “The Lion King,” has mixed feelings about some of these issues. “Brokeback Mountain” he considers “a beautiful film” that moved him deeply when it came out. But 17 years later, if that movie was made again, Eichner thinks it would be a “more affecting and a more ethical production” if those characters were played by openly gay actors.

“That’s not taking away from the fact that Heath Ledger is brilliant in that movie. No one would deny that Sean Penn is magnificent in ‘Milk.’ No one would deny that Tom Hanks is wonderful in ‘Philadelphia,'” Eichner says. “Tom Hanks, though — and I was so impressed and grateful for him saying this publicly — said recently that if ‘Philadelphia’ was made today, he wouldn’t have gotten the role and he said that would have been the right thing to do. In 1992, you needed Tom Hanks to play a gay man dying of AIDS because the movie wouldn’t have gotten the financing it required, it wouldn’t have gotten a wide release and, on some level, straight people wouldn’t have been comfortable with it.”

Eichner, 43, is acutely aware of the not-so-long-ago Hollywood history that leads up to “Bros.” Only a handful of years ago — and today isn’t so hunky-dory, either, Eichner cautions — coming out for gay performers meant sacrificing their career. Eichner, himself, has previously been told by a theater agent to “tone down” his gayness.

“And those were the options up until, I don’t know, a couple of years ago. ‘Bros’ is the antithesis to all of that,” says Eichner. “It’s not just a symbol because it is a living, breathing movie that I think is very successful creatively in its own right having nothing to do with representation or the historical nature of it. But on top of it being a really funny movie, it is a symbol of progress.

“It really is, honestly, just kind of a big f—- you to the history of Hollywood and how it’s treated LGBTQ people behind the scenes.”

The “Billy on the Street” persona of Eichner’s — arch, satirical — isn’t his character in “Bros,” though they share some qualities. It was important to Eichner that his character and the film’s love interest, played by Luke Macfarlane, be complex, three-dimensional characters, not an absurdist version of a gay man — not stereotypical sidekicks.

“Billy on the Street” opened with a mock theme song that introduced him as “making dreams come true.” But with “Bros,” Eichner may have genuinely done so — probably for many others but definitely for himself.

“It’s far and away the best thing I’ve ever done,” Eichner says. “I’m allowed to be a fully, multi-dimensional human being. It’s not identical to me but you can tell when you watch the movie, this really is the most accurate glimpse of everything that I am.”