Lightroom Classic will permit Editing in the Photoshop Elements Editor application. Where Photoshop CC is not installed, it appears automatically in prefs as the principal external editor – see image below.
But there is presently a glitch when using Ctrl+E or Cmd+E or Edit In from the Lr Classic grid.
The Editor launches, but without the photo. At this point, customers will often quit the PSE Editor or go back to the Lr Library and try again. BUT WAIT!
If you return to the Lr Library and wait one and a half minutes an error message appears. When clicking Ok to dismiss the message the Lr Taskbar shows “Preparing file for editing” and the image magically appears in the PSE Editor.
Obviously this is not a great performance but with a little know-how and patience it is possible to carry out the external editing in elements with the saved image going back into the Lr Library next to the original photo.
I always recommend setting the prefs to render 8 bit PSD files as there is limited functionality for 16 bit images.