Not really sure but I might be able to prove ownership of certain addresses I used in past which are of exchange's addresses.
Note that for signing a message from a bitcoin address, you need to have full control over the address. This means that you must own the private key of the address.The deposit address an exchange gives you isn't owned by you. That's owned by the exchange and you can't sign a message from that.
I know, and I agree with you
The addy exchanges give to me isn't owned by me, but the account in those exchanges are owned by me...anyways I don't have any private key to any of the non custodial wallet addresses which I have used for bounties since I disposed them off while taking a break and I staked only one address only to later find I have disposed the seed phrase of it. It's been done before, and I think the recovery team will accept it.
I have deleted all of the handful of non-custodial wallets that I used for bounties since it's a hassle to have so many of them instead of just having one. So idk if I can move any funds from those. Maybe I can move funds from the wallet addresses which are of my exchange accounts. I'm not trying to recover my account, just wanted to address the fact that I have lost access to the staked address because I have disposed off the seed phrase after uninstalling the wallet. So I wanted to stake a new address.