I posted this a while back, came across a post on hackaday on doing clear lens on a resin printer with lower effort, the article links an older one about doing clear resin prints that might be helpful. To me they look pretty decent, certainly a heck of a lot better than any transparent prints I’ve done with a filament printer.

As others said though, easiest would probably be doing something like laser cut acrylic and sandwiching the picture between them.