Yes, it's sad to think that the problem you bring up about Tumblr deletions only contributes to the problem of content loss in other places.

If you do decide to go the Google Photos route, you can set up a new account for just fandom use with a pseud. And let me know if you have any questions. The workaround tool that someone else shared with me is https://ctrlq.org/google/photos/

You get the photo link from G Photos, put it in there and it generates the image embed code for you. Because the direct photo link doesn't work for embedding. An extra step, but I have had no problems with it.