There are still some, though not many, free hosting sites that let you link to images. One free site I use quite often is https://postimages.org/
but I'm afraid that most sites are now paid subscription only and I don't know how long that site will last.
I should add that apart from the Photo section on the forums, embedding images in FT chat/messageboards is not allowed. In other words, you can post a link to an image hosted elsewhere but you can't use code that lets people see the image on the chatboard page itself. However, for most purposes a link is all you need so good luck.
PS If they're nice photos, post them on the forums anyway!