> Can you be invited to their homes as well?
Yes.
> Do relationships seem a bit more in-depth?
Eh. Depends, I guess. Audie has said the moon wolf thing to me literally 9 days in a row as her first dialogue box of the day.
For some reason, seeing Cephalobot and Ione felt like they had absolutely new dialogue and were entirely differently scripted for several days, though. My friend feels the same with Quinn. So there must be new dialogue added. It isn't exclusive to the new villagers, as I've since gotten some of the others to say the same stuff now, but it felt cool, lol.
In any case, dialogue is not any less repetitive in NL. Yes, some things are much shorter in NH, and yes, it seems less like they want to talk to you repeatedly because they seem to get annoyed with you faster by pointing it out after like, sometimes even just the second time you talk to them, but it's really not better, haha. People are having nostalgia goggles on the dialogue in NL ... It's the previous games that had the most depth. But, to each their own, I guess. Try it and see how it feels, tbh.
> do villagers interact more with items placed outside, in their homes, your home, etc.?
Mostly, they like to look at items outside. Some they can play with, but I don't have an extensive list. I put down a warp pipe yesterday and three of my villagers have stopped to gawk at it, lol. They don't interact with or care about my ABD, wooden shed, or clothes locker, though. ( I have nothing else placed rn because I'm remodeling, but!! )
They do interact with their own in - home items, I think the same ones they can interact with outside. I visited my friend's Dom and he was bouncing his yoga ball for awhile, lol.
They comment on items inside your home and sit on your chairs. Not sure about anything else, though,