iPhone 15 2 bluetooth headsets at once

You'd have to go old school and use a Y splitter cable and wired earbuds that are sitting in a drawer or you can buy a Bluetooth transmitter that can pair up two headsets. There are a few options on Amazon and Primecables.

If you have any sets of AirPods 2nd Gen or later, AirPods Pro, AirPods Max, or specific Beats Headphones, you can. But AirPods and Beats are the only supported headphones you can play music with Audio Sharing.

Hope this helps!

"...I know of no devices made by anyone that allow you to connect two pairs of wireless headphones to listen at the same time..." is SO WRONG, because most non-Apple phones let you do it easily. And that's a huge problem. Apple locks you into their ecosystem as much as possible: if you have an Apple device, you can fully use most of its features only with other Apple devices, not the device you want. For example, I have beautiful Sennheiser TW 3 headphones, and my gf has the same.

We both love the sound much more than the sound of AirPods (it's our personal preference), but since we can't use them with our iPhones at the same time, when we fly on an airplane we always bring our Galaxy Note with us to connect both headphones to one device and enjoy our movies. And it sucks because I like iOS and don't like to have one more extra device that I wouldn't need to carry once Apple wouldn't be that restrictive.

No, sorry. It's not.

Use earbuds, and put one in one persons ear and the other in the other persons ear. I know of no devices made by anyone which let you connect two pairs of wireless headphones to listen to at the same time.