Reading some of your comments, I think this may get to it...
The Viable part is key here. What makes a product Viable will be category dependent.
Every category has its Kano curve. If you're creating a new category, or entering one early on, the must-haves will hopefully be a small set. In this case, your MVP can be fairly simple.
If you're entering a more mature category, your competitors will have likely established a baseline of must-haves that you will need, plus whatever differentiating features you are bringing. In this case, your MVP will be more complex.
In both cases, you would be building an MVP, but viability will be very different.
UI/UX rapidly becomes a must-have as categories evolve, but, as others have said (with the very apt OpenAI example), if you're early enough and are bringing something suitably exciting, UI/UX can wait a bit.
Reading some of your comments, I think this may get to it...
The Viable part is key here. What makes a product Viable will be category dependent.
Every category has its Kano curve. If you're creating a new category, or entering one early on, the must-haves will hopefully be a small set. In this case, your MVP can be fairly simple.
If you're entering a more mature category, your competitors will have likely established a baseline of must-haves that you will need, plus whatever differentiating features you are bringing. In this case, your MVP will be more complex.
In both cases, you would be building an MVP, but viability will be very different.
UI/UX rapidly becomes a must-have as categories evolve, but, as others have said (with the very apt OpenAI example), if you're early enough and are bringing something suitably exciting, UI/UX can wait a bit.