Satchonsims and pixelade have got to play this game early on youtube.

I watched SatchonSims' build video. I like how it looks, but since it's multiplayer, I'm just not interested in this one.

So on their Steam forums there are some answers to obvious questions :

Q: so in the latest vid i watched about multiplayer is this game only just about building or will their be other vivaland npcs too romance instead of romancing your friend?
A: There will also be NPCs in the early access of the game!

Q: Will there be modsupport?
A: Coming from a team who are mod supporters, we would love to make this possible in the future!

So, npc's will be added at some point and no actual confirmation of mod support in that answer. The described active careers on the store page are very minimal. They talk about romance, but without npc's yet, its romancing the people you play with in multiplayer :/
I don't think npc's or mods can be an afterthought in a sims like game. So, imo this does not look like a sims alternative.

I'm sure the bolded part won't get all kinds of messy. Yikes!

Eww, Nope!

https://youtu.be/zkxTLKnpV-I?si=MOvvxpYXm37lGui3

I downloaded the building demo and found it somewhat tricky to use, but came up with something acceptable in the end and they have time to fix things. My main concern is about the size of the world which felt quite small, and the number of buildable plots was very limited.
I haven't seen all the publicity about this game, because right now it is hard to keep up with all the info that is out there for life sim games, but it feels like Vivaland might not make sense for a solo game player, that the design is being optimised as a casual game to play with friends.

I downloaded the demo too and I thought everything about it was boring.