If you're interested in something like that maybe you'll like Atashi wa Bambi. It's on the shorter side but still a slow burn. I remember really enjoying it 20 years ago and this is just an excuse for me to recommend it honestly lol
Looked it up and wow I love when shoujos touch upon queerness with tact! It's a genre so commonly cishet that when they have queer characters in the background that are accepted as queer instead of othered or reformed it is amazing. I don't really like the art style though, but thank you for the rec. I put it on my lists, maybe one day I'll pick it up
I said this under another comment but I'll say it again:
I wouldn't mind him being bi if he never showed actual interest in her until we're 80 chapters in and it's a gradually developed slow burn with a lot of tact when dealing with the theme of being LGBTQ+ and thinking you already figured everything about yourself but now you're finding out your labels all over again and your head is a mess and sometimes people don't fit perfectly into labeled square boxes because humans are complex. But that might be too much to expect from a comedy gag manga. Either way, I'm happy with them being platonic, that is also refreshing.