Lol had to try 🤷‍♂️

Depending on how you look at it, this might be kinda the opposite of what you’re asking for, but I thought I’d throw it out anyway in case you may still be interested: The Ideal Sponger Life is about a Japanese salaryman who gets isekai’d (willingly and intentionally, for a change) and marries the queen of a desert nation who needs a husband for political reasons but is reluctant to marry any of her statesmen (again, for political reasons).

The manga/novel (hasn’t been animated just yet) mainly focuses on the political relationships between the nations of the isekai world, and the MC struggling to figure out how to reconcile his cultural differences while also being a decent diplomat for the sake of his nation and his wife.

Part of that is the fact that MC’s marriage was initially purely political, but he and the queen grow to genuinely love each other. However, polygyny is the common practice in this new nation, especially among aristocrats, so MC is basically required to have a harem of wives, even though he very much doesn’t want any other than the queen. This results in him having to find clever, politically acceptable ways to avoid advances from (shrewd, surprisingly well written) women who want to join his harem to garner power for their families.

In summary: It’s a political fantasy story that is only technically a harem, and even then it’s not ecchi/oblivious MC/blah, but an integral part of the political intrigue in the story. Don’t know if that’s still a deal breaker for you, but just give the first volume or two a shot. I went in with very low expectations and was blown away with how well the worldbuilding and characters were executed.

Divine Gate was exceedingly mid (not surprising, it’s based off a mobile game), but its OP One Me, Two Hearts is a banger

For manga, I’ve always purchased from Barnes & Noble and Books a Million, mainly because they’re near my house and I’m more of an in-store shopper, but they’ve got solid online presences and a satisfying catalogue. Plus, both have pretty good membership reward programs (B&N in particular is $40/yr and gives you 10% off pretty much everything, free shipping, and a $5 reward for every cumulative $100 spent, plus some other stuff).

And if those places don’t have what I’m looking for, there’s always Amazon

I regret to inform you that your girlfriend is a robot

Oh damn, you’re definitely right about Fairy Tail. It’s been so long since I’ve watched it I completely forgot about all the fanservice. It’s bizarre though, because if it wasn’t for that it’d fit right in with other “Saturday morning” kids anime like Yu-Gi-Oh and Pokemon

My Hero Academia is also violent, but it’s a bit less graphic than Demon Slayer, and it’s themed around super heroes/villains so the concept may be more approachable for a child. It’s one of my personal favorites, but fair warning: The themes do get somewhat more mature as the show goes on.

If your kid has an interest in science, Dr. Stone could be a great fit. Contains some violence, but it’s mostly about a super genius recreating modern technology using primitive resources after an apocalypse.

Another one in the science vein, Cells at Work tells the story of anthropomorphic cells living and doing their jobs in a human body. Again, some violence, but it’s mostly cartoonish and shouldn’t be much of a worry for a kid.

Fairy Tail is also a good choice, especially since its audience skews younger than the other recs I’ve given here. It follows a group of wizards at a famous guild as they take on quests and go on adventures. Very kid-friendly with a huge backlog of episodes.

On second thought, maybe give Fairy Tail a miss due to the fanservice. I apparently blocked all those scenes from my memory when watching as a kid.