Chipolo has announced a Find My-enabled card for slipping into a wallet. I do not like that the battery is non-replaceable, but I pre-ordered one anyway for keeping up my with my wallet.
As Matt VanOrmer writes, this plugs a big hole in the Find My universe:
When I got the MagSafe Leather Wallet with Find My, I was hoping for a solution that would A. Hold my credit cards and B. Help me find my wallet if I lost it. While it succeeds at A, it fails spectacularly at B. Chipolo has created a product that would actually help me find my wallet if it were lost or stolen.