Did some digging and the Photon or Photon S can read .photons or .photon files in addition to .pws with the newest 5.0.2 firmware.
V5.0.2
(1) Allow Photon S and Photon Upgraded to support .photon, .photons, .pws files
(2) After upgrade, the UI will be changed to UI 2.6, and the firmware version will be
changed to P_V502. 1.2. How to upgrade UI and Firmware for Photon S and Photon Upgraded
Instructions
(1) Extract the firmware package to obtain the “P_V502.bin” and “P_UI_2_6.bin” files, and
then copy these two files to an empty USB flash drive. [DO Not store other files in the
U disk to avoid interference; DO NOT modify the file name]
(2) Insert the USB flash drive into the Photon S or Photon Upgraded and switch it on. (3) Select the "Print" menu on the screen, and then select and print the "P_V502.bin" file
and the "P_UI_2_6.bin" file to upgrade one by one. Note:
1. It will take about a few minutes to upgrade the "P_UI_2_6.bin" file. Please be patient. 2. After the upgrade finished, you can view the system version through the "System" -->
"Information" menu on the display
Source: https://drucktipps3d.de/wp-content/uploads/asgarosforum/60526/Firmware-V5.0.2-Upgrade-Guide-for-Photon-S-and-Photon-Upgraded-20191109.pdf
Firmware Download (Photon): https://www.anycubic.com/blogs/videos/videosall-you-need-to-know-about-photon
Firmware Download (Photon S): https://www.anycubic.com/blogs/videos/all-you-need-to-know-about-anycubic-photon-s