PSB format is used for Adobe Photoshop graphics, for files that are exceptionally large (larger than 300,000 x 300,000 pixels), to make them distinguished from the standard PSD format. But except for this, they are pretty much the same format, with just different extension.
Thus any software that can be used for png to psd conversion can be used for png to psb conversion as well, provided they support the exceptionally large file size. Of course using Photoshop is best option.
Updated: November 3, 2023