In 2018 in an interview with the Huffington Post, Solo co-screenwriter Jonathan Kasdan, when asked if he viewed Lando Calrissian as pansexual, replied "I would say yes. There's a fluidity to Donald and Billy Dee's [portrayal of Lando's] sexuality," Kasdan continued. "I mean, I would have loved to have gotten a more explicitly LGBT character into this movie. I think it's time, certainly, for that, and I love the fluidity ― sort of the spectrum of sexuality that Donald appeals to and that droids are a part of. He doesn't make any hard and fast rules. I think it's fun. I don't know where it will go."
Daniel Glover confirmed this, saying "How can you not be pansexual in space? There's so many things to have sex with. I mean, serious. I didn't think that was that weird. Yeah, he's coming on to everybody. I mean, yeah, whatever. He's like having like a '70s swing — yeah. It just didn't seem that weird to me 'cause I feel like if you're in space it's kind of like, the door is open! It's like, no only guys or girls. No, it's anything. This thing is literally a blob. Are you a man or a woman? Like, who cares? Have a good time out here."
However there's a world between a writer or actor saying something, and it appearing on the screen. And suggested flirting between Han Solo and Lando in the Solo movie could just have been in the eye of the beholder.
But in June, Marvel Comics is running a series of Pride Covers featuring LGBTQ+ characters in the Star Wars universe, many – such as Doctor Aphra and Sana Starros – were created for the comic book line. The Marvel Star Wars comics are considered official canon by Lucasfilm, and lots of effort goes into making the canon, canon.
So when Marvel Comics added Lando Calrissian to the LGBTQ+ Marvel Pride covers, approved by LucasFilm, that is as official canon as anything else. And may indicate a certain direction for the upcoming Lando TV series.