Photoshop CS5 doesn't seem to natively support saving image as APNG even tho few of the major browsers already support it. Are there any export plugins or such available for Photoshop?
For 24-bit/32-bits APNG: In Photoshop (File - Export - Render Video), then use apngasm. Checked method.
Photopea photo editor can open APNG (and GIF) and place each frame into a separate layer. Then, you can download it as a layered PSD.
It can also convert a layered PSD into APNG (or GIF), while placing each layer into a separate frame. You can find more details here.
Photopea is basically "Anything to PSD" and "PSD to Anything".
** I am an author of Photopea and I would be very glad to get some feedback about this new feature :)