-DeviantArt it's very strict about photos/screenshots of videogames (SL falls in this category sadly in that site no exceptions).
-Artstation it's only for post your own model or artwork creations no photos,screenshots or music
-Instagram follow the same rules as facebook (PG/sfw) and the rest of their products. they tend to "hunt" flag time to time SL accounts and flagging them as fake earning a ban temp or permanent
-500px only allows IRL photography and pg
-Furaffinity it's a virtual gallery too but it's for the furry fandom it allows all 3 ratings pg(sfw), moderate and restricted (NSFW) but same as devianart it's strict about photos/screenshots of videogames (they consider sl as a game just like deviant). and as experience from there too. ppl of that site tend to have a lot of scam bots, hate sl or be really creepy with users in general
-Twitter. twitter allows anything but it's a social network never was designed as web photo gallery, even if some creators or sl community peeps use it, has flaws and sometimes if the system fails it flags/shadow ban the photos or delete them
Other idea is if LL host their own community photos dashboard like some south korean mmorpgs do (example: https://aion.plaync.com/board/image/list ) but that's a lot of work to set up, make sure each photo that is uploaded uses the correct classification rating sfw, moderate, nsfw and follows the sl tos