Sorry to hear that. Perhaps someone picked it up and will return it to you. There's that hope.

As a rule I always carry my wallet and phone either on me or in my backpack. Like you found out, losing all the documents and cards in my wallet is more than the hassle of losing anything else on the bike combined. The phone is there so I can hear it if it rings. My panniers are used for everything else.

I did lose a saddle mounted camera one time. I went to turn off the camera after arriving home to find that it wasn't there anymore. I rode back half way to see if I could find it. No luck. The next day on the way home I spotted it about 1 km from my work, right up against the curb of the sidewalk partially covered by leaves. I turned it on, and lo and behold, it still worked. I got lucky.