Like a year ago i saw a game wich was very simmilar to 3dxchat. It was on kickstarter. I dont remember the name. It looked much better and im corious if its out or what.
It might have been one of the 2 games made in UE5 which Match3D & Meredian are both working on. One is a Spanish team that's much smaller and the other is a Russian team, but I haven't heard any news on both of them.
If by single player you mean go through animations without having to interact with another used you can create a second avatar and spawn them in your home without needing another user.