The only way I have found is to follow this workflow:
1. Go to google photos on a browser (chrome)
2. Find the photo and open it in google photos. You should see the share button on the top right - don?t use this. This just links to the album and you can?t embed a photo on the forum using this link.
3. Instead, push and hold on the photo until the menu appears and then select ?open image?.
4. This will open the photo in a browser window and the address in the address bar is the **permanent** link you can use to embed a photo here.
** this is kind of permanent. Not all users will be able to see it for geographical reasons (or somebthing) and I think it can expire. Not sure how long you get. But enough to use for a discussion etc. Maybe some google experts can explain this part as I am not sure.
As a test - here is an embedded photo...
Holding breath:
