closest i’ve come to finding something like it is this manga sweet trap. i’d really like suggestions.
The game Hades is fairly bisexual. It has a super thirsty fan base… and I love every bit of it.
Check out the manga Blue Flag.
Pillars of Eternity II is a cRPG in the vein of Baldur’s Gate and a lot of the party is bi/pan. There’s four romanceable characters who are into men and women, one who is only into women but shares his body with his previous reincarnation who likes men. It’s not a primary feature of the game though, closer to Bioware style romance where it doesn’t have a ton of impact on the plot.
True Blood
Rocky Horror Picture Show
Dragon Age, Stardew Valley, and the Sims all have multi-gender romance options where you can pursue multiple partners at the same time.