List of institutions showing their proof of reserves on-chain:

1) MetaPlanet (https://metaplanet.mempool.space/wallet/3350)

2) River (http://river.com/reserves)

3) El Salvador (https://bitcoin.gob.sv/address/32ixEdVJWo3kmvJGMTZq5jAQVZZeuwnqzo)

Who else???

Thanks!