Julot135
Do you have limitations on the platform and plugins you can use?
I have an app in NWJS for PC desktop which I can open photos and save (Invoice generator).
Using NWJS and Paster objects you can give the user an open dialogue, load in a picture and save the picture as a string in base64 format. (Very long text).
I am guessing this could then be sent across multiplayer to another user. I am afraid I've not done anything with the multiplayer plugin yet so I would nowt know about this part. (I only made a multiplayer game about 4 years ago with PeerJS)