I think the announcement thing could actually serve a pretty reasonable social purpose. Letting others around you know how you're doing and how you feel, as well as making cooperation go a bit more smoothly and clearing up confusion. Secrecy and privacy still has some benefits, but it would usually be best for yukkuri to be super clear and honest with their families and groups.
Pet yukkuri are actually really interesting. If they were real, I'd be interesting in having a couple for myself.
The only thing is that they often seem to require a lot of breeding and training to get that way, and I often feel like the stories are kinda implying that yukkuri are usually inherently awful and stupid, and getting them to gold/platinum level is almost a miracle.
I remember a comic where a really kind and well behaved gold-badge Reimu still ended up horribly abused and corrupted just for the hell of it... That's probably the most a yukkuri story has ever genuinely upset and frustrated me. I almost wanted to write a fixer fic just to feel better about it.
I've also had a few more ideas exploring underestimated yukkuri , and the general idea of a world where the common opinion on yukkuri is actually pretty misinformed and "racist", with a lot of yukkuri that don't actually follow all preconceptions about their qualities.
Like an Anon discovering a yukkuri that uses "I" for herself and actually asks him his name instead of calling him mister.
Said Yukkuri getting offended when he says she's "supposed" to speak 3rd person and only call him mister.
"Do I look like a baby to you, Haru?"
Repeat offensive assumptions and arguments until the yukkuri leaves in a huff and Haru is just totally dumbfounded.
You could also throw in some things that are still true, which could be used for more comedy.
"I suppose you're going to go 'yunya' now, aren't you?"
"Yunya! Don't be rude, Haru! I never say yunya!"
"You just did."
This is now the main reason yukkuri are shitty towards humans: Humans are racist and condescending as hell XD.
I also think it would be a pretty interesting idea to have a story where pet stores and breeders sort of have a conspiracy going where they /claim/ that getting gold badge yukkuri is really tricky and difficult and only experts can manage it, so that they can justify really high prices for the best yukkuri and make it so consumers don't want anything else. They could also have misleading caretaking/punishment advice that makes it seem like "oh, your dumb little regular yukkuri is a lost cause, you better come buy a gold badge yukkuri!"
Then someone takes in a supposed "trash" yukkuri and manages to teach it manners and get it to behave well in only a week or two (not gold, but still way better than anyone thought), by doing some experimenting, critically examining the supposed "expert advice", and modifying anything that doesn't seem to add up.
Repeated experiments continually show that most yukkuri actually have a lot more gold badge potential than people are led to believe, and the truth of this slowly spreads, from both the main character and from other people who were also curious and resourceful enough to discover the truth.
The result would be a story where abyuse could actually dramatically /decrease/ by the end of it.