Well, I'd highly suggest "Our Life: Beginnings and Always." I played it on Steam! I think you could download it on here if you prefer, though. It's such a breathtaking game. Not only is it LGBTQ+ friendly (well, your only love interest is a male, but you are allowed to choose your own gender/pronouns). There's so, so many other features to it as well that just make it perfect for me. The DLCs are also so heartwarming, everything is just chefs kiss worthy!
They're also coming out with a second game. Our Life: Now and Forever. You can play the Demo on Steam or on here. It's hinted that the full game might be coming out in the fall.
Our Life: Beginnings and Always is based in the summer, this new game is based in the fall. They said it'll come out "when the season is right". I might be wrong, but I took it as a hint nevertheless.
I'd also suggest Saint Spell, which is here on itch.io. And then there's the game When The Night Comes. None of these are internet chatroom based, but they're all LGBTQ+ friendly and interesting in their own ways! I very much favor Our Life more, however. So I'd highly, highly suggest playing that one first if you haven't already.
Of course, this game is old, so you've most likely already played it―but there's Mystic Messenger, which is a chatroom based game that you can only download on your phone. It used to be incredibly popular. And while the fandom is long dead by now, there are a few remaining who are very much alive. Like me.
Mystic Messenger is... debatable on LGBTQ+ elements, but it still has its great moments and storyline. Then again, there is one woman (other than you in the game) named Jaehee! But while she does have her own route, it's a platonic one. I think? That's why I said it's debatable. Her route confuses me to no end. I just headcanon her as "she has feelings for the MC but she's stuck in the closet".
In Blooming Panic, I did notice that "xyx" has a similar personality and role in the story to a character in Mystic Messenger, named "707". While "nightowl" is also similar to a character in Mystic Messenger, named "Yoosung". Of course, they're all still very different characters with their own good and bad attributes! But if you haven't played Mystic Messenger yet, you might enjoy the similarities in these characters.
Here are two others I'll quickly mention: The Arcana, which you can download on your phone. My opinion on this game is rocky. While I appreciate the artstyle and storyline, there are often (far too often, in my opinion) options where you have to pay. And they're always the most interesting options. It sucks, and I haven't finished the game due to that.
There's also Twisted Wonderland. Which isn't a dating game nor chatroom based, and whoo boy do I have my own strong critiques on the game, but I still love so many of the characters, storyline, and artstyle.
Well, I hope I helped you out! All of these besides Mystic Messenger aren't similar to Blooming Panic at all. So I'm sorry for that, but I do hope I still helped somewhat. I also want to note that The Arcana is the only game I listed with paid options, so no need to worry with the others.