This article places the origin of “bring home the bacon” to an African American boxer’s mother in 1906. He mentions gravy in the response, so I suspect they’re talking about bacon as in meat from the back half of a pig, like a bone-in pork leg rather than the sliced pork belly we envision today. The (figurative) bacon he was encouraged to bring home would be a big piece of meat like a roasted ham.
Tangentially, this makes me think about how much recently-introduced slang is for basically-random reasons like "it happened fit well into the rhyme and meter of a popular song" or "somebody attractive/famous said it" or "it sounds cool and kids' parents hate it".
Maybe there's a good reason for the bacon thing, or maybe some guy just tended to buy bacon on payday. /shrug
Not limited to recent slang, really - consider all the early 1900s slang that's now part of the language. "Bee's knees," "beat it," "cat's meow," and lots of others. Somebody tested out those phrases and they stuck.
"It sounds cool and kids' parents hate it" goes back to at least the 50s. It's an arms race of kids/teens trying to invent their own slang that their parents won't understand and then that language being picked up in popular culture and becoming more widely used and then kids try to come up with new terms.
(We had a lot of fun with "yeet," "hype," "been knew," and a few others with my kids a few years ago.)
Cockney rhyming slang also comes to mind. I have to believe "it sounds cool and kids' parents hate it" goes back even farther than that though, probably ever since there have been kids and parents!
https://jonathanbecher.com/2020/06/14/bring-home-the-bacon/