"Boomer" is internet slang for a (usually, but not necessarily, older) person with little awareness of the internet and its culture. It doesn't have any strong connection to proper baby boomers. The opposite would be a "zoomer" - a young person who is unaware of older internet culture or perhaps just culture in general. A Facebook person who doesn't know what Fortnite is would be a boomer; a TikTok kid who doesn't know what the dancing baby meme is or who Michael Jackson is would be a zoomer.