Photo sharing app??

I used The Guest as a guest back in 2017 before it was rebranded. It was very easy to use. I don’t remember many guests utilizing it, but there were quite a few pictures from those who did.

Honestly, guests aren’t going to download an app just to send you photos. I would stick with normal social media or just have them send you photos via text.

I have not heard of those. I use With Joy for my wedding website and the app has a feature where guests can share their photos to it. I haven't used that part of it yet but I thought it was a good idea.
You said you were looking into a videographer, but have you hired a photographer? I wouldn't rely on guests photos alone.

I read your post a few days ago and I didn't even know these things existed...so I did a little research of my own. I think I might try and use one of these myself as I think it will be an awesome way to collect photos from people but I am concerned no one will use it, haha. I like "Wedding Photo Swap" the best out of what I've looked at. Seems you can use both an app or the website to upload so you dont have to have all your guests use an app if thats an issue. They have both pay and free plans to choose from as well.

I recently tried Photo-Space.live as a guest and it turned out to be a pretty convenient service. I can't say that everyone actively used it, but those who uploaded photos left quite a few pictures.