There is nothing at all being copied but an aesthetic.
Although to me it is interesting that, even without literal copying, a generator might be capable of potentially emulating some key features of a specified source. Can this sometimes arguably extend beyond just "an aesthetic"? We've all seen examples similar to this one (from the SD online demo, default setting, with a familiar public-domain source) — https://i.imgur.com/PUJs3RL.png
see also this previous discussion:
https://kbin.social/m/selfhosted@lemmy.world/t/182362/What-are-your-backup-solutions
Thanks for a reminder that I should look into userscripts for kbin. — For now, I'm using the Stylus extension (in desktop Firefox & Chrome) to apply custom CSS. Nothing fancy yet, just simple overrides to remove some margins and padding to make the "compact" view more compact.
In another discussion someone mentioned the "wefwef" Apollo-inspired Lemmy client. I haven't looked into it myself, but apparently some users like it, so maybe consider adding it to your list?
[Later Edit: — I see that the list has been updated, and wefwef has been added.]