• Cheery would 100% march in the parade. She'd get Nobby to go with her, but Nobby would be completely oblivious as to why (he assumed she just wants company).
• Moist von lipwig would have pride-themed stamps made; these would inevitably have some kind of issue, which would create some outrage and ultimately make the stamps more valuable as collectors' items.
• I don't get the impression that Ankh Morpork ever had anti-sodomy or crossdressing laws, so I don't think the queer community's history with the police would be the same as it is in the real world. Especially because Cheery Littlebottom literally started the Dwarf trans/feminism movement as an officer of the Watch, with the Watch's support.
• Dibbler would totally sell pride flags with the wrong colors (and then insist it was the "new, updated version" if anyone questioned him)
• The nobility are all scandalized, meanwhile the Seamstresses Guild has a float in the parade
• Adora Belle Dearheart is deeply involved with at least one queer organization and is one of the main organizers of the Pride festival, but refuses to answer any questions about why
• Ridcully decides the wizards should be involved, and Ponder Stibbons should make a float and organize the refreshments for them to eat while riding on the float. Ridcully's concept of allyship is loudly saying, "Well done, that man!" and pointing at anyone he thinks is exhibiting particularly queer behavior.
• Madam Sharn and Pepe release a whole new line of Pride-themed chainmail
• Bengo Macarona is embraced as a gay icon
• Reg Shoe decides the main pride event is too corporate, and organizes an alternative pride parade for the same time and place; this immediately gets subsumed by the main pride event. Some Omnians show up to Pride to protest and Reg is delighted to have someone to fight with.

“The scent rolled over him. He looked up. Overheard, a lilac tree was in bloom. He stared. Damn! Damn! Damn! Every year he forgot. Well, no. He never forgot. He just put the memories away, like old silverware that you didn’t want to tarnish. And every year they came back, sharp and sparkling, and stabbed him in the heart. And today, of all days… He reached up, and his hand trembled as he grasped a bloom and gently broke the stem. He sniffed at it. He stood for a moment, staring at nothing. And then he carried the sprig of lilac carefully back up to his dressing room.”

The flower buds were noticeably swelling. He stood and stared, as a man might stare at an old battlefield… 

“Don’t put your trust in revolutions. They always come around again. That’s why they’re called revolutions.”

The new sergeant-at-arms picked up his badge with care and saluted yet again. ‘Oath, sir,’ he said.

‘Oh, er, that thing? Er, I believe I’ve got it written down somewh—’

Vimes took a deep breath. This probably wasn’t a good idea, but he was flying now.