The best simulation games like Viva Pinata are Slime Rancher 2, Stardew Valley and Ooblets. Below are 8, each with the reason it is here — and, at the end, what filtering to simulation costs you.
Filtering to simulation means you want a system to run or a routine to inhabit. It is the right filter when what you liked was being somewhere rather than beating something.
What you get: A game that does not need you to be good at it, and that rewards paying attention over reacting quickly.
What made Viva Pinata worth playing in the first place is covered on the full list. This page is the simulation part of that answer, and only the simulation part.
Creature husbandry with the same tinkering loop and the same bright tone.
The gentlest deep systems game there is, and endlessly replayable.
Farming plus creature collecting, in the same cheerful register.
Open-ended, no fail state, animals to look after.
If designing the space rather than the food chain was the appeal.
Genuinely strange creature-breeding systems under a cute surface.
The series that established the whole shape of this genre.
Caring for characters with individual needs, and beautifully made.
Urgency. Simulations are deliberately slow, and the ones with no fail state give you nothing to push against.
Specifically, these are strong answers for Viva Pinata that are not simulation games, so they are not on this page:
The full list is on games like Viva Pinata — 9 picks, no genre filter.
Slime Rancher 2. Creature husbandry with the same tinkering loop and the same bright tone.
No. Viva Pinata released on the Xbox 360, but a recommendation is only useful if you can play it, so the picks above span platforms and eras. What they share is the genre and the reason.
A simulation with no fail state and no time pressure. The label describes how it feels to play rather than what genre it is in.
No — one is about running a system well, the other about inhabiting a routine. Recommending across that line is where most simulation recommendations go wrong.
By hand. Each pick was written for the full Viva Pinata list first, on what the game actually does, and this page is the part of that list that is simulation — never a genre tag lookup, which is how "best racing games like Super Mario 64" used to be a page on this site.
Or read the simulation guide for where to start in the genre generally.