You made a great guide, but it does not relate to account recovery procedure in the forum. I still don't know the purpose of secure, and prove ownership of Ethereum address in the forum, if you simply want to prove it for use cases outside the forum space.
Anyway, I thank you for this great guide for community.
You're right, signed message from ETH or any other altcoin address isn't accepted for account recoveries here. Probably because it's
BITCOIN forum.
But still, this guide is very useful. For example, signing message from ETH address will help you to verify that you hold funds. This stuff can be used if you are dealing with escrow or lending money.