There are a ton of suggestions here already, but I wanted to add my favorite:

Danskin Intimates Laser Cut Lounge Bra

They can be hard to find, but they are the absolute closest thing I’ve found to wearing nothing at all, while still having enough smoothing to be presentable.

I can actually stand to wear it all day even when I don’t have to be wearing a bra. It’s super thin super smooth material, minimal seams, light straps, feels like almost nothing. They have removable cups that I always take out, but even without them it’s enough shaping and support for people-ing. I absolutely recommend giving them a try.

There are different styles, but this is one of the ones I have:

https://www.amazon.com/Danskin-Wirefree-Everyday-Bralette-Removable/dp/B08NTHL98B