This is not really directly about resizable BAR. you could do mostly the same api without it. Resizable bar simplifies it a little bit because you skip manual transfer operations, but its not completely required as you can write things to a cpu-writeable buffer and then begin your frame with a transfer command.

Bindless textures never needed any kind of resizable BAR, you have been able to use them since early 2010s on opengl through an extension. Buffer pointers also have never needed it.