Last year, #Flickr said they are studying it. We haven't heard any updates since.

I would suggest using #Pixelfed for your photos since you can upload more than 4 images through it. Or, any other Fediverse software; avoid Mastodon when it comes to images/gallery: (1) you can only upload max 4 images; and (2) anything beyond 4 attachments, Mastodon sends it to the blackhole. It's not a bug, it's by-design, still, it should be “fixed”.

I post most of my photos here - https://www.flickr.com/photos/mgifford

I'd love to have #Flickr just jump onto #ActivityPub so they could all be in one place.

Until then. Here are some photos of France.